Sieve of Eratosthenes

eratosthenes.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import sys

def eratos(n):
    nums = dict([(x, 1) for x in range(2, n)])

    for x in range(2, n):
        i = 2
        while (x * i) < n:
            if x * i in nums:
                del(nums[x * i])
            i += 1

    return nums.keys()

if __name__ == "__main__":
    num = 100
    if len(sys.argv) > 2:
        num = int(sys.argv[1])

    print(eratos(num))