fastPrime.py

import sys
import time

s = time.time()
N = int(sys.argv[1])
prime = [True]*N

prime[0] = False
prime[1] = False

for i in range(2, int(N**0.5)):
    if prime[i]:
        for j in range(i*2, N, i):
            prime[j] = False

ans =  [i for i in range(N) if prime[i] == True]
print ans, len(ans), time.time()-s