PyPE solution to PE problem 41

    ProjectEuler.net problem 41
    ===========================

    We shall say that an n-digit number is pandigital if it makes use of all
    the digits 1 to n exactly once. For example, 2143 is a 4-digit pandigital
    and is also prime.

    What is the largest n-digit pandigital prime that exists?

    Solution
    --------

    we generate successively shorter lists of [9,8,7,6,5,4,3,2,1], ..., [2,1]
    and then look at all of the permutations of the list. Once a prime number
    is found, we return that number, as it is the correct solution.

    Answer
    ------

    7652413