Randomly find a number which satisfies Luhn's algorithm

random.py

#!/usr/bin/env python
import random

def digits_of(number):
    return [int(i) for i in str(number)]

def luhn_checksum(card_number):
    digits = digits_of(card_number)
    odd_digits = digits[-1::-2]
    even_digits = digits[-2::-2]
    total = sum(odd_digits)
    for digit in even_digits:
        total += sum(digits_of(2 * digit))
    return total % 10

def is_luhn_valid(card_number):
    return luhn_checksum(card_number) == 0

def make_random_num():
    return ''.join(map(lambda x: str(random.randrange(0,9)),range(16)))

random_num = make_random_num()

while (not is_luhn_valid(random_num)):
    print "Invalid: " + random_num
    random_num = make_random_num()

print "Valid: " + random_num