Project Euler 24 - Lexicographic Permutations

'''
A permutation is an ordered arrangement of objects. For example, 3124 is one possible permutation of the digits 1, 2, 3 and 4.
If all of the permutations are listed numerically or alphabetically, we call it lexicographic order. The lexicographic permutations of 0, 1 and 2 are:
012   021   102   120   201   210
What is the millionth lexicographic permutation of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9?
'''
def factorial(n):
    if n < 0 or n != int(n):
        return None
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)

from itertools import permutations
N = 10
targetIndex = 1000000
perm = permutations(range(0, N))
# Check condition
if targetIndex > factorial(N):
    print("There is not such a permutation.")

counter = 0
for p in perm:
    # print(p)
    counter += 1
    if counter == targetIndex:
        print("The lexicographic permutation of a list from 0 to " + str(N-1) + " in index " + str(targetIndex) + " is: " + str(p))
        break