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 A307920 #14 Feb 16 2025 08:33:55 %S A307920 0,0,4,704,553008,13802629632,1782158930138112,14231924675064000331776 %N A307920 Number of (undirected) Hamiltonian cycles in the n X n black bishop graph. %H A307920 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/BlackBishopGraph.html">Black Bishop Graph</a> %H A307920 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a> %F A307920 a(n) = A282889(n)/2. %Y A307920 Cf. A282889, A307929. %K A307920 nonn,hard,more %O A307920 2,3 %A A307920 _Eric W. Weisstein_, May 06 2019 %E A307920 Offset corrected and a(2) prepended by _Pontus von Brömssen_, Nov 22 2020