def isirreducible(n):
    if (n.real**2 == 1 and n.imag**2 == 1):
        return True
    elif (n.real % 4 == 3 and isprime(n.real) and n.imag == 0):
        return True
    elif(n*n.conjugate() % 4 == 1 and isprime(n*n.conjugate())):
        return True
    return False
示例#2
0
def mySimulate():
    a = 1
    b = 0
    c = 0
    d = 0
    e = 0
    f = 0
    g = 0
    h = 0

    b = 81
    c = b
    if a != 0:
        b = 108100
        c = b + 17000
    else:
        b = 81
        c = b

    while True:
        f = 1

        if not isprime(b):
            h += 1

        if c == b:
            return h
        b += 17
def find_prime_power(N):
    for i in range(2, int(math.log(N, 2) + 1)):
        [flag, b] = find_largest_b(N, i)
        if flag == 1:
            if isprime(b):
                return [b, i]
    return str(N) + " is not a prime power"
示例#4
0
def test_prps():
    oddcomposites = [n for n in range(1, 10**5) if
        n % 2 and not isprime(n)]
    # A checksum would be better.
    assert sum(oddcomposites) == 2045603465
    assert [n for n in oddcomposites if mr(n, [2])] == [
        2047, 3277, 4033, 4681, 8321, 15841, 29341, 42799, 49141,
        52633, 65281, 74665, 80581, 85489, 88357, 90751]
    assert [n for n in oddcomposites if mr(n, [3])] == [
        121, 703, 1891, 3281, 8401, 8911, 10585, 12403, 16531,
        18721, 19345, 23521, 31621, 44287, 47197, 55969, 63139,
        74593, 79003, 82513, 87913, 88573, 97567]
    assert [n for n in oddcomposites if mr(n, [325])] == [
        9, 25, 27, 49, 65, 81, 325, 341, 343, 697, 1141, 2059,
        2149, 3097, 3537, 4033, 4681, 4941, 5833, 6517, 7987, 8911,
        12403, 12913, 15043, 16021, 20017, 22261, 23221, 24649,
        24929, 31841, 35371, 38503, 43213, 44173, 47197, 50041,
        55909, 56033, 58969, 59089, 61337, 65441, 68823, 72641,
        76793, 78409, 85879]
    assert not any(mr(n, [9345883071009581737]) for n in oddcomposites)
    assert [n for n in oddcomposites if is_lucas_prp(n)] == [
        323, 377, 1159, 1829, 3827, 5459, 5777, 9071, 9179, 10877,
        11419, 11663, 13919, 14839, 16109, 16211, 18407, 18971,
        19043, 22499, 23407, 24569, 25199, 25877, 26069, 27323,
        32759, 34943, 35207, 39059, 39203, 39689, 40309, 44099,
        46979, 47879, 50183, 51983, 53663, 56279, 58519, 60377,
        63881, 69509, 72389, 73919, 75077, 77219, 79547, 79799,
        82983, 84419, 86063, 90287, 94667, 97019, 97439]
    assert [n for n in oddcomposites if is_strong_lucas_prp(n)] == [
        5459, 5777, 10877, 16109, 18971, 22499, 24569, 25199, 40309,
        58519, 75077, 97439]
    assert [n for n in oddcomposites if is_extra_strong_lucas_prp(n)
            ] == [
        989, 3239, 5777, 10877, 27971, 29681, 30739, 31631, 39059,
        72389, 73919, 75077]
示例#5
0
def test_prps():
    oddcomposites = [n for n in range(1, 10**5) if
        n % 2 and not isprime(n)]
    # A checksum would be better.
    assert sum(oddcomposites) == 2045603465
    assert [n for n in oddcomposites if mr(n, [2])] == [
        2047, 3277, 4033, 4681, 8321, 15841, 29341, 42799, 49141,
        52633, 65281, 74665, 80581, 85489, 88357, 90751]
    assert [n for n in oddcomposites if mr(n, [3])] == [
        121, 703, 1891, 3281, 8401, 8911, 10585, 12403, 16531,
        18721, 19345, 23521, 31621, 44287, 47197, 55969, 63139,
        74593, 79003, 82513, 87913, 88573, 97567]
    assert [n for n in oddcomposites if mr(n, [325])] == [
        9, 25, 27, 49, 65, 81, 325, 341, 343, 697, 1141, 2059,
        2149, 3097, 3537, 4033, 4681, 4941, 5833, 6517, 7987, 8911,
        12403, 12913, 15043, 16021, 20017, 22261, 23221, 24649,
        24929, 31841, 35371, 38503, 43213, 44173, 47197, 50041,
        55909, 56033, 58969, 59089, 61337, 65441, 68823, 72641,
        76793, 78409, 85879]
    assert not any(mr(n, [9345883071009581737]) for n in oddcomposites)
    assert [n for n in oddcomposites if is_lucas_prp(n)] == [
        323, 377, 1159, 1829, 3827, 5459, 5777, 9071, 9179, 10877,
        11419, 11663, 13919, 14839, 16109, 16211, 18407, 18971,
        19043, 22499, 23407, 24569, 25199, 25877, 26069, 27323,
        32759, 34943, 35207, 39059, 39203, 39689, 40309, 44099,
        46979, 47879, 50183, 51983, 53663, 56279, 58519, 60377,
        63881, 69509, 72389, 73919, 75077, 77219, 79547, 79799,
        82983, 84419, 86063, 90287, 94667, 97019, 97439]
    assert [n for n in oddcomposites if is_strong_lucas_prp(n)] == [
        5459, 5777, 10877, 16109, 18971, 22499, 24569, 25199, 40309,
        58519, 75077, 97439]
    assert [n for n in oddcomposites if is_extra_strong_lucas_prp(n)
            ] == [
        989, 3239, 5777, 10877, 27971, 29681, 30739, 31631, 39059,
        72389, 73919, 75077]
示例#6
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def prime_list():
    """Create prime number list below 1000000"""
    L = []
    for n in range(1, 1000000):
        if isprime(n):
            L.append(n)
    return L
示例#7
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def shor(N):
    if isprime(N):
        print('{} is a prime'.format(N))
        return -1
    if N % 2 == 0:
        print('{}: N is even'.format(N))
        return 2
    for i in range(3, int(np.log2(N))):
        j = i
        while (j <= N):
            if j == N:
                print(str(N) + ': trivially, N={}^a for some int a'.format(i))
                return i
            j *= i
    while (1):
        x = random.randint(2, int(np.sqrt(N)))
        if (np.gcd(x, N) != 1):
            print('{}: by randoming, got factor {}'.format(N, np.gcd(x, N)))
            return (np.gcd(x, N))
        #print('Attempting: N={}, x={}'.format(N,x))
        r = quantum_find_r_sped(x, N)
        #print('found r={}'.format(r))
        if (r % 2 == 1): continue
        #print('(N,x,r)=({},{},{})'.format(N,x,r))
        a = np.gcd((x**(int(r / 2)) - 1) % N, N)
        #print('a={}, ie {}'.format(a, int(a)))
        if (a == 1 or a == N): continue
        print('{}: Found (N,x,r)={},{},{} with factor {}'.format(
            N, N, x, r, np.gcd(int(a), N)))
        return np.gcd(int(a), N)
    def __init__(self, p, g, y, name="Verifier"):
        """
        Initializes the verifier. Checks the validity of the arguments, and sets the public parameters p, g, y.

        This method has to initialize instance variables p, g and y (c and b will remain unset until choose_b method
        is called).

        :param p: integer, modulus
        :param g: integer, base
        :param y: integer, g^x mod p
        :param name: optional string, name of the verifier (to be used when printing data to the console)
        """
        self.p = None
        self.g = None
        self.y = None
        self.c = None
        self.b = None
        self.name = name

        try:
            assert (isprime(p))
            assert (y < p)
            assert (is_primitive_root(g, p))

        except:
            raise InvalidParams

        self.p = p
        self.g = g
        self.y = y

        print_debug("{}:\t\tInitialized with p = {}, g = {} and y = {}".format(
            self.name, self.p, self.g, self.y), LOG_INFO)
示例#9
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def LargestPrimeFactor(n="NAN"):
    if n == "NAN":
        n = int(input("LargestPrimeFactor(n), n = "))
    num = str(n)
    rng = int(np.sqrt(n))
    primes = np.array(primeslist(1, rng))
    val = n
    while isprime(val) == False:
        vals = np.linspace(val, val, len(primes))
        print(vals)
        divs = vals / primes
        print(divs)
        counter = 0
        for i in range(len(primes)):
            if int(divs[i]) == divs[i]:
                print(divs[i], " for ", primes[i])
                val = divs[i]
                print(val)
                if val == 1:
                    LPF = primes[i]
                    print("The largest prime factor of ", num, " is ", LPF)
                    return LPF
                else:
                    break
            else:
                counter += 1
                if counter == len(primes):
                    print("loop encountered")
                    LPF = val
                    print("The largest prime factor of ", num, " is ", LPF)
                    return LPF
示例#10
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def is_prime_as_int(n0: Union[int, float, complex]) -> int:
    n = cint(n0)
    if n != n0: return 0
    try:
        from sympy.ntheory.primetest import isprime
    except ModuleNotFoundError:
        raise Exception("Install sympy to use number-theoretic functions!")
    # Note: If it ever matters, nonpositive integers are not prime.
    return int(isprime(n))
 def is_exatly_prime_64(num):
     """
     Точная проверка того, простое ли (True) или составное (False) число,
     работает только в диапазоне [0, 2*64)
     """
     if num >= 2**64:
         raise ValueError(
             "Эта функция работает только в диапазоне [0, 2*64)")
     return primetest.isprime(num)
 def inv_fermat(self, a, n):
     if isprime(n):
         if a < 0:
             a = a % n
         b = a
         for i in range(n - 3):
             b = b * a % n
         return b
     else:
         return "n is not prime"
示例#13
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 def generatesMaxSequence(self):
     ''' 
     The length K of a multiplicative congruence generator
     satisfies the following properties:
     - If K = M-1, then M is prime
     - K divides M -1
     - K = M - 1 if and only if a is a primitive root of M and M is prime
     '''
     res = isprime(self.moduli) and isPrimitiveRoot(self.a, self.moduli)
     return res
示例#14
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def primegenerating(n):
    if is_square(n):
        return 0
    for div in divisors(
            n
    ):  #unfortunately a generator does not work, as it does not order the divisors, and we would break out of the loop too soon.
        if div * div > n:
            break
        if not isprime(div + (n // div)):
            return 0
    return n
示例#15
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文件: solve.py 项目: jdclarke5/sylver
def quick(position):
    """Quick tests for whether the position status is known."""
    # All enders/quiet-enders are N except {2, 3}.
    # Note that [1] is irreducible (p) according to our definitions
    if position.gcd == 1 and position.irreducible \
            and position.generators != [2, 3]:
        return "N"
    # Single primes greater than 3 are P
    if len(position.generators) == 1 and position.generators[0] > 3 \
            and isprime(position.generators[0]):
        return "P"
示例#16
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def N(a, b):
    primes = []
    for n in range(max(abs(a), abs(b))):
        num = f(n, a, b)
        #        print(num)
        if isprime(num):
            primes.append(num)
        else:
            break
    nprimes = len(primes)
    return (nprimes)
示例#17
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def solve1(printflag, allflag, b):
    sols = canned1.get(b)
    if sols:
        if printflag:
            for sol in sols:
                print("{}!".format(sol))
                if not allflag:
                    break
        return sols[0]
    if isprime(b):
        return 0
    raise ValueError("Cannot solve {{{}}}".format(b))
示例#18
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def peel_right(i):
    """"Remove digits right to left,
    then check for prime number"""
    x = list(str(i))
    for n in range(1, len(x)):
        y = x[:(-n)]
        s = int(''.join(y))
        if isprime(s):
            continue
        else:
            return "False"
    return "True"
def generate_prime_number(length=1024):
    """ Generate a prime
    Args:
        length -- int -- length of the prime to generate, in bits
    return a prime
    """
    p = 4
    # keep generating while the primality test fail
    while not isprime(p):
        p = generate_prime_candidate(length)
    # print("prime generated: %d" %p)
    return p
示例#20
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def generate_primes():
    p = None
    q = None
    while (p == None) or (q == None):
        odd_rand_num = random.randrange(100000, 999999)
        if isprime(odd_rand_num):
            if p == None:
                p = odd_rand_num
            else:
                q = odd_rand_num
    print("Your private key is: ", (p, q))
    return (p, q)
示例#21
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def quadratic_primes(arange):
    a, b, max_n = [0, 0, 0]
    for i in prime_sieve(arange + 1):  # b must be prime
        for j in range(-i + 2, 0, 2):
            n = 1
            while isprime(
                    n * n + j * n + i
            ):  # equation= n^2 +  a*n + b, it has to generate prime numbers
                n += 1
                if n > max_n:
                    a, b, max_n = j, i, n
    return a * b
示例#22
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 def check_prime(self, n):
     """
     Функция проверки простоты числа (используется класс Primes из библиотеки sage)
     Parameters
     ----------
     n : Union[int, gmpy2.mpz]
         Число для проверки
     Returns
     -------
     bool
         Простое ли число
     """
     return isprime(int(n))
示例#23
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def naive_search(M, N, J):
    p = np.array([0] * N)
    p[0], p[-1] = 1, 1
    jamcoins = []
    proofs = []
    for i in range(0, 2**(N - 2)):
        p_ = [int(a) for a in str(bin(i))[2:]]
        p[-(len(p_) + 1):-1] = p_
        c = [sum([a * b for a, b in zip(p, D)]) for D in M]
        if all([not isprime(a) for a in c]):
            jamcoins.append("".join([str(a) for a in p]))
            proofs.append([min(list(factorint(a).keys())) for a in c])
            if len(jamcoins) == J:
                break
    return jamcoins, proofs
示例#24
0
 def __init__(self, p, n=1):
     p, n = int(p), int(n)
     if not isprime(p):
         raise ValueError("p must be a prime number, not %s" % p)
     if n <= 0:
         raise ValueError("n must be a positive integer, not %s" % n)
     self.p = p
     self.n = n
     if n == 1:
         self.reducing = [1, 0]
     else:
         for c in itertools.product(range(p), repeat=n):
             poly = (1, *c)
             if gf_irreducible_p(poly, p, ZZ):
                 self.reducing = poly
                 break
示例#25
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def add_primes(primes, switch):
    """Return the last number in the list (largest prime),
    and the in-loop counter (consecutive numbers)"""
    counter = switch  # start with this prime number
    in_counter = 0
    sum = 0
    L = []
    while sum < 1000000:
        sum = sum + primes[counter]
        if isprime(sum):
            L.append(sum)
        in_counter += 1  # in loop counter
        counter += 1
    if L[-1] < 1000000:
        return L[-1], in_counter
    elif L[-1] > 1000000:
        print("****")
        return L[-2], in_counter
示例#26
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def main_code(x):
    N, J = tuple(map(int, input().split()))
    current = 1 + (2**(N - 1))
    print("Case #" + str(x + 1) + ":")
    for _ in range(J):
        prime = True
        while prime:
            jamcoin = format(current, 'b')
            current += 2
            prime = False
            proof = []
            for base in range(2, 11):
                interpretation = int(jamcoin, base)
                if isprime(interpretation):
                    prime = True
                    break
                else:
                    proof.append(str(primefactors(interpretation)[0]))

        print(jamcoin, " ".join(proof))
示例#27
0
def compute_min_length():
    cur_value = 1
    num_primes = 0

    for spiral_radius in itertools.count(1):
        gap_between_diagonals = 2 * spiral_radius

        # For each of the first three corners
        for _ in range(3):
            cur_value += gap_between_diagonals
            if isprime(cur_value):
                num_primes += 1

        # Ignore the bottom right corner
        cur_value += gap_between_diagonals

        # There are 4 corners in each spiral, and one center number
        prime_ratio_of_diagonal = num_primes / (4 * spiral_radius + 1)
        if prime_ratio_of_diagonal < 0.1:
            return spiral_radius * 2 + 1
示例#28
0
def number_replacement(combo, digit_dict, prime_set):
    prime_list = []
    not_prime = 0

    for digit in range(0,10):
    	
    	test_dict = dict(digit_dict)
    	for pos in combo:
    		test_dict[pos] = digit
		new_dig = int(''.join([str(x) for x in test_dict.values()]))
		
		#make sure the number hasn't been shortened by a leading zero
		if len(str(new_dig)) == len(digit_dict.keys()):
			if isprime(new_dig):
				prime_list.append(new_dig)
			else:
				not_prime += 1
				if not_prime > (10 - prime_set):
					return []
	return prime_list
示例#29
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def quadratic_primes(max_coefficient):
  '''Calculate the product of the coefficients that generate the most primes
  for a sequence of n starting with n=0 of the form:

  n^2 + an + b

  for |a| < max_coefficient and |b| < max_coefficient.
  '''

  b_lst = list(sieve.primerange(1, max_coefficient))

  max_n = 0
  for a in range(-max_coefficient + 1, max_coefficient):
    for b in b_lst:
      n = 0
      while isprime(n**2 + a * n + b):
        n += 1
      if n > max_n:
        max_n = n
        max_product = a * b

  return max_product
示例#30
0
    def __init__(self, p, g, y, x, name="HonestProver"):
        """
        Initializes the prover. Checks the validity of the arguments, sets the public parameters p, g, y and sets the
        secret x.

        This method has to initialize instance variables p, g, y and x (r will remain unset until compute_c method
        is called).

        :param p: integer, modulus
        :param g: integer, base
        :param y: integer, g^x mod p
        :param x: integer, secret
        :param name: optional string, name of the prover (to be used when printing data to the console)
        """

        self.p = None
        self.g = None
        self.y = None
        self.x = None
        self.r = None
        self.name = name

        try:
            assert (isprime(p))
            assert (y < p)
            assert (is_primitive_root(g, p))
            if x is not None:
                assert (pow(g, x, p) == y)
        except:
            raise InvalidParams

        self.p = p
        self.g = g
        self.y = y
        self.x = x

        print_debug("{}:\tInitialized with p = {}, g = {}, y = {} and x = {}".format(
            self.name, self.p, self.g, self.y, self.x), LOG_INFO)
示例#31
0
 def __init__(self, p, n=None):
     if n is None:
         L = primeFact(p)
         if len(set(L)) > 1:
             raise ValueError('order must be a prime power')
         p = L[0]
         n = len(L)
     p, n = int(p), int(n)
     if not isprime(p):
         raise ValueError("p must be a prime number, not %s" % p)
     if n <= 0:
         raise ValueError("n must be a positive integer, not %s" % n)
     self.p = p
     self.n = n
     if n == 1:
         self.reducing = [1, 0]
     else:
         for c in itertools.product(range(p), repeat=n):
           poly = (1, *c)
           if gf_irreducible_p(poly, p, ZZ):
               self.reducing = poly
               break
     self.iterpos = 0
示例#32
0
文件: modular.py 项目: alhirzel/sympy
def solve_congruence(*remainder_modulus_pairs, **hint):
    """Compute the integer ``n`` that has the residual ``ai`` when it is
    divided by ``mi`` where the ``ai`` and ``mi`` are given as pairs to
    this function: ((a1, m1), (a2, m2), ...). If there is no solution,
    return None. Otherwise return ``n`` and its modulus.

    The ``mi`` values need not be co-prime. If it is known that the moduli are
    not co-prime then the hint ``check`` can be set to False (default=True) and
    the check for a quicker solution via crt() (valid when the moduli are
    co-prime) will be skipped.

    If the hint ``symmetric`` is True (default is False), the value of ``n``
    will be within 1/2 of the modulus, possibly negative.

    Examples
    ========

    >>> from sympy.ntheory.modular import solve_congruence

    What number is 2 mod 3, 3 mod 5 and 2 mod 7?

    >>> solve_congruence((2, 3), (3, 5), (2, 7))
    (23, 105)
    >>> [23 % m for m in [3, 5, 7]]
    [2, 3, 2]

    If you prefer to work with all remainder in one list and
    all moduli in another, send the arguments like this:

    >>> solve_congruence(*zip((2, 3, 2), (3, 5, 7)))
    (23, 105)

    The moduli need not be co-prime; in this case there may or
    may not be a solution:

    >>> solve_congruence((2, 3), (4, 6)) is None
    True

    >>> solve_congruence((2, 3), (5, 6))
    (5, 6)

    The symmetric flag will make the result be within 1/2 of the modulus:

    >>> solve_congruence((2, 3), (5, 6), symmetric=True)
    (-1, 6)

    See Also
    ========

    crt : high level routine implementing the Chinese Remainder Theorem

    """
    def combine(c1, c2):
        """Return the tuple (a, m) which satisfies the requirement
        that n = a + i*m satisfy n = a1 + j*m1 and n = a2 = k*m2.

        References
        ==========

        - http://en.wikipedia.org/wiki/Method_of_successive_substitution
        """
        a1, m1 = c1
        a2, m2 = c2
        a, b, c = m1, a2 - a1, m2
        g = reduce(igcd, [a, b, c])
        a, b, c = [i//g for i in [a, b, c]]
        if a != 1:
            inv_a, _, g = igcdex(a, c)
            if g != 1:
                return None
            b *= inv_a
        a, m = a1 + m1*b, m1*c
        return a, m

    rm = remainder_modulus_pairs
    symmetric = hint.get('symmetric', False)

    if hint.get('check', True):
        rm = [(as_int(r), as_int(m)) for r, m in rm]

        # ignore redundant pairs but raise an error otherwise; also
        # make sure that a unique set of bases is sent to gf_crt if
        # they are all prime.
        #
        # The routine will work out less-trivial violations and
        # return None, e.g. for the pairs (1,3) and (14,42) there
        # is no answer because 14 mod 42 (having a gcd of 14) implies
        # (14/2) mod (42/2), (14/7) mod (42/7) and (14/14) mod (42/14)
        # which, being 0 mod 3, is inconsistent with 1 mod 3. But to
        # preprocess the input beyond checking of another pair with 42
        # or 3 as the modulus (for this example) is not necessary.
        uniq = {}
        for r, m in rm:
            r %= m
            if m in uniq:
                if r != uniq[m]:
                    return None
                continue
            uniq[m] = r
        rm = [(r, m) for m, r in uniq.iteritems()]
        del uniq

        # if the moduli are co-prime, the crt will be significantly faster;
        # checking all pairs for being co-prime gets to be slow but a prime
        # test is a good trade-off
        if all(isprime(m) for r, m in rm):
            r, m = zip(*rm)
            return crt(m, r, symmetric=symmetric, check=False)

    rv = (0, 1)
    for rmi in rm:
        rv = combine(rv, rmi)
        if rv is None:
            break
        n, m = rv
        n = n % m
    else:
        if symmetric:
            return symmetric_residue(n, m), m
        return n, m
示例#33
0
def test_isprime():
    s = Sieve()
    s.extend(100000)
    ps = set(s.primerange(2, 100001))
    for n in range(100001):
        # if (n in ps) != isprime(n): print n
        assert (n in ps) == isprime(n)
    assert isprime(179424673)
    assert isprime(20678048681)
    assert isprime(1968188556461)
    assert isprime(2614941710599)
    assert isprime(65635624165761929287)
    assert isprime(1162566711635022452267983)
    assert isprime(77123077103005189615466924501)
    assert isprime(3991617775553178702574451996736229)
    assert isprime(273952953553395851092382714516720001799)
    assert isprime(int('''
531137992816767098689588206552468627329593117727031923199444138200403\
559860852242739162502265229285668889329486246501015346579337652707239\
409519978766587351943831270835393219031728127'''))

    # Some Mersenne primes
    assert isprime(2**61 - 1)
    assert isprime(2**89 - 1)
    assert isprime(2**607 - 1)
    # (but not all Mersenne's are primes
    assert not isprime(2**601 - 1)

    # pseudoprimes
    #-------------
    # to some small bases
    assert not isprime(2152302898747)
    assert not isprime(3474749660383)
    assert not isprime(341550071728321)
    assert not isprime(3825123056546413051)
    # passes the base set [2, 3, 7, 61, 24251]
    assert not isprime(9188353522314541)
    # large examples
    assert not isprime(877777777777777777777777)
    # conjectured psi_12 given at http://mathworld.wolfram.com/StrongPseudoprime.html
    assert not isprime(318665857834031151167461)
    # conjectured psi_17 given at http://mathworld.wolfram.com/StrongPseudoprime.html
    assert not isprime(564132928021909221014087501701)
    # Arnault's 1993 number; a factor of it is
    # 400958216639499605418306452084546853005188166041132508774506\
    # 204738003217070119624271622319159721973358216316508535816696\
    # 9145233813917169287527980445796800452592031836601
    assert not isprime(int('''
803837457453639491257079614341942108138837688287558145837488917522297\
427376533365218650233616396004545791504202360320876656996676098728404\
396540823292873879185086916685732826776177102938969773947016708230428\
687109997439976544144845341155872450633409279022275296229414984230688\
1685404326457534018329786111298960644845216191652872597534901'''))
    # Arnault's 1995 number; can be factored as
    # p1*(313*(p1 - 1) + 1)*(353*(p1 - 1) + 1) where p1 is
    # 296744956686855105501541746429053327307719917998530433509950\
    # 755312768387531717701995942385964281211880336647542183455624\
    # 93168782883
    assert not isprime(int('''
288714823805077121267142959713039399197760945927972270092651602419743\
230379915273311632898314463922594197780311092934965557841894944174093\
380561511397999942154241693397290542371100275104208013496673175515285\
922696291677532547504444585610194940420003990443211677661994962953925\
045269871932907037356403227370127845389912612030924484149472897688540\
6024976768122077071687938121709811322297802059565867'''))
    sieve.extend(3000)
    assert isprime(2819)
    assert not isprime(2931)
    assert not isprime(2.0)