ambi_sieve_plain Python

def sum_of_primes_for(n):
    s = range(3, n, 2)
    for m in xrange(3, int(n**0.5)+1, 2): 
        if s[(m-3)/2]: 
            for t in xrange((m*m-3)/2,(n>>1)-1,m):
                s[t]=0
    return sum([2]+[t for t in s if t>0])
    
#>>> sum_of_primes_for(2000000)
#142913828922