26 lines
400 B
Python
26 lines
400 B
Python
#!/usr/bin/env python3
|
|
|
|
def primes(n):
|
|
sieve = [False] * n
|
|
for p in range(2, n):
|
|
if sieve[p]:
|
|
continue
|
|
for i in range(p**2, n, p):
|
|
sieve[i] = True
|
|
return sieve
|
|
|
|
bound = 10**6
|
|
sieve = primes(bound)
|
|
c = 0
|
|
|
|
n = 1
|
|
cube_diff = 7
|
|
|
|
while cube_diff < bound:
|
|
if not sieve[cube_diff]:
|
|
c += 1
|
|
n += 1
|
|
cube_diff = 3*n**2 + 3*n + 1
|
|
|
|
print(c)
|