Euler #71

#!/usr/bin/env python

from fractions import gcd

N = 1000000

for d in xrange(2, N):
    for n in xrange(3*d/7+1, 1, -1):
        if n*7 < 3*d:
            if gcd(n,d) == 1:
                res = (n, d)
                break;

print(res)