Is fraction integer for any n?

#!/usr/bin/env python

#http://math.stackexchange.com/questions/517429/

from fractions import Fraction


def gen():
    num = 0
    den = 0
    k = 1
    while True:
        num += k**k
        den += k
        yield Fraction(num, den)
        k += 1

if __name__ == "__main__":
    n = 1
    for number in gen():
        if number.denominator == 1:
            print("n = %i works!" % n)
            if n > 1:
                break
        if n % 100 == 0:
            print("n = %i does not work :-(" % n)
        n += 1