Roumanos prime 3

a = [2, 3, 5, 7, 11, 13, 17, 19]
for num in range(3, 100000000, 2):
    prime = True
    for y in a:
        if num % y == 0:
            prime = False
            break
    if prime:
        a.append(num)
print (a[10001])