Project Euler, Problem #10, Python

#! /usr/bin/env python3

# The task: the sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find
# the sum of all the primes below two million.

s = set()
r = 2

for m in range(2, 1000001):
    for u in range(2 * m, 2000001, m):
        s.add(u)

for i in range(3, 2000001, 2):
    if not i in s:
        r += i

print(r)

# 142913828922
# 25326301 function calls in 19.818 seconds