Sieve of Eratosthenes - Finding Primes Python

Question

Just to clarify, this is not a homework problem :)

I wanted to find primes for a math application I am building & came across Sieve of Eratosthenes approach.

Answer 1

The fastest implementation I could come up with:

isprime = [True]*N
isprime[0] = isprime[1] = False
for i in range(4, N, 2):
    isprime[i] = False
for i in range(3, N, 2):
    if isprime[i]:
        for j in range(i*i, N, 2*i):
            isprime[j] = False