findPrimesSum.py

import math

n = 2000000

def primesTo(lim):
	primes = [2]
	t = 0
	sieve = [False] * lim

	crosslim = int(math.sqrt(lim))

	for i in range(3, lim, 2):
		sieve[i] = True

	for i in range(3, crosslim, 2):
		if not sieve[i-1]: #hence prime
			for k in range((i-1)*2+1,lim,i):
				sieve[k] = True


	for i in range(1, lim):
		if not sieve[i]:
			t = t + i + 1


	print t


	return t

primesTo(n)