This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A342631 #40 Feb 16 2025 08:34:01 %S A342631 1,1,3,238,48828036 %N A342631 Number of Hamiltonian paths (or Gray codes) on n-cube with the origin as the starting node, up to a permutation of the coordinates. %H A342631 Luc Rousseau, <a href="/A342631/a342631.c.txt">A C program that computes a(n)</a> %H A342631 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianPath.html">Hamiltonian Path</a> %H A342631 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HypercubeGraph.html">Hypercube Graph</a> %F A342631 a(n) = A003043(n) / n!. %e A342631 For n=2, the two Hamiltonian paths of the square that start at (0,0), i.e., %e A342631 (0,0) -->-- (1,0) (0,0) (1,0) %e A342631 | | | %e A342631 V and V ^ %e A342631 | | | %e A342631 (0,1) --<-- (1,1) (0,1) -->-- (1,1), %e A342631 only account for one, as one is obtained from the other by the x <-> y permutation; so a(2) = 1. %o A342631 (C) /* See Rousseau link. */ %Y A342631 Cf. A003043, A091299. %K A342631 nonn,hard,more %O A342631 1,3 %A A342631 _Luc Rousseau_, May 24 2021