The Hanoi graph H_n corresponding to the allowed moves in the tower of Hanoi problem. The above figure shows the Hanoi graphs for small n. The Hanoi graph H_n can be constructed by taking the vertices to be the odd binomial coefficients of Pascal's triangle computed on the integers from 0 to 2^n - 1 and drawing an edge whenever coefficients are adjacent diagonally or horizontally.

puz-graph | Sierpiński gasket graph | tower of Hanoi