https://en.wikipedia.org/wiki/Riffle_shuffle_permutation#Perfect_shuffles https://en.wikipedia.org/wiki/Riffle_shuffle_permutation#Per... Shows that perfect sh

https://en.wikipedia.org/wiki/Riffle_shuffle_permutation#Perfect_shuffles https://en.wikipedia.org/wiki/Riffle_shuffle_permutation#Per... Shows that perfect shuffles can return the deck to the original state.