sieve.py

LIMIT = 20001
NATURALS = range(3,LIMIT, 2)
PRIMES = [2]
current = 0
max = LIMIT

while len(NATURALS) > 0:
    current = NATURALS.pop(0)
    PRIMES.append(current)
    i = current
    try:
        max = NATURALS[-1]
    except IndexError:
        break
    while i <= max:
        i = i + current
        try:
            NATURALS.remove(i)
        except ValueError:
            pass

print('primes: {0}'.format(PRIMES))
print('sum: {0}'.format(sum(PRIMES)))

LIMIT = 2000001
NATURALS = range(3,LIMIT, 2)
PRIMES = [2]
current = 0

while len(NATURALS) > 0:
current = NATURALS.pop(0)
PRIMES.append(current)
try:
n = NATURALS[-1] / current
except IndexError:
pass
i = current
while n > 1:
i = n * current
try:
NATURALS.remove(i)
except ValueError:
pass
n -= 1

print('sum: {0}'.format(sum(PRIMES)))