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 A269561 #14 Feb 16 2025 08:33:30 %S A269561 1,48,284112,335750676480,112249362914249932800, %T A269561 14994936423694913432308324761600 %N A269561 Number of (undirected) Hamiltonian cycles in the n X n rook graph K_n X K_n. %H A269561 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a> %H A269561 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RookGraph.html">Rook Graph</a> %Y A269561 Cf. A269562, A096970, A003763, A222199. %K A269561 nonn,more %O A269561 2,2 %A A269561 _Andrew Howroyd_, Feb 29 2016 %E A269561 Name adjusted by _Eric W. Weisstein_, May 06 2019