The solution is practically identical to the one from [Mathblog](http://www.mathblog.dk/project-euler-70-investigate-values-of-n-for-which-%CF%86n-is-a-permutation-of-n/).
But Kristian explains it much better than I :).

We use our trustworthy [Sieve of Eratosthenes](https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes) snippet and the *GetCombinatoricHash*-function from problem-62

The rest was straight-forward and not really that interesting. 