def is_truncatable(p):
p_str = str(p)
if len(p_str) == 1:
return False
for length in range(1, len(p_str)):
trunc_left = p_str[:length]
trunc_right = p_str[-length:]
if not (is_prime(int(trunc_left)) and is_prime(int(trunc_right))):
return False
return True
def testPrimeOrNot(self):
primes = [2, 3, 5, 7, 11, 13, 17, 19, 23]
i = 0
for j in range(2, 24):
if is_prime(j):
self.assertEqual(primes[i], j)
i += 1
def test_permutations(digits):
permuted_digits = itertools.permutations(digits)
vals = sorted(set([digits_to_num(p) for p in permuted_digits]))
subseqs = find_arithmetic_subsequences(vals)
prime_subseqs = []
for seq in subseqs:
if all([is_prime(n) for n in seq]):
prime_subseqs.append(seq)
return prime_subseqs
def solve_with_permutations():
# Go through all possible pandigital numbers from largest to smallest
for num_digits in range(9,0,-1):
digits = [str(i) for i in range(num_digits, 0, -1)]
permutations = itertools.permutations(digits)
for permutation in permutations:
n = int(reduce(concat, permutation))
if is_prime(n):
return n
def disprove_goldbach():
def satisfies_goldbach(n):
for p in primes[primes < n]:
r = n - p
if sqrt(r / 2).is_integer():
return True
return False
for n in itertools.count(9, 2):
if is_prime(n):
continue
if not satisfies_goldbach(n):
return n
def testBuzzFizzForPrimesRegression(self):
for i in range(4, 100):
if is_prime(i) and i != 3 and i != 5:
self.assertEqual("BuzzFizz", fizzbuzz(i))