3: towers of Hanoi

There's a very good book by Hinz, Klávžar, Milutinović and Petr, called "Towers of Hanoi - Myths and Maths".
It collects all sorts of theorems and perspectives on the puzzle, and plenty of variants.
A Mastodon instance for maths people. The kind of people who make $\pi z^2 \times a$ jokes.
Use $ and $ for inline LaTeX, and $ and $ for display mode.