Решето Эратосфена

N = 121
simple = [True]*(N+1)
for x in range(2, int(N**0.5) + 1):
    if simple[x]:
        y = x*x
        while y <= N:
            simple[y] = False
            y += x
for x in range(2, N):
    if simple[x]:
        print(x, end=' ')
print()