def main(n):
limit = (2 * ((n + 1)**2)) - 1
p = Prime()
primes = p.sieve(limit)
d = {
x:True for x in primes
}
res = []
for i in range(2, n + 1):
t = (2 * (i**2)) - 1
if t in d:
res.append(t)
return len(res)
def triangles(): i = 3 count = 3 while True: prime = Prime() prime_factors = prime.factor(i) mul = 1; for key, amount in prime_factors.items(): mul *= (amount + 1) if mul > 500: return i i += count count += 1
def largest_prime_factor(n): prime = Prime() return max(prime.factor(n).keys())