Here’s a neat visualization: https://old.reddit.com/r/dataisbeautiful/comments/r9b8uz/oc_8_perfect_shuffles_shuffling_a_deck_of_cards/
Along with more detailed explanation: The Perfect Shuffle | Towards Data Science and even more math: https://mathweb.ucsd.edu/~ronspubs/83_05_shuffles.pdf
I’ll let Wendell explain it, though!