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 A222200 #22 Jul 02 2025 10:10:20 %S A222200 1,2,14,154,5320,301384,49483138,13916993782,10754797724124, %T A222200 14746957510647992,53540340738182687296,354282765498796010420944, %U A222200 6040964455632840415885507728,191678405883294971709423926242394,15351055042300622367048024911122943712 %N A222200 Number of Hamiltonian cycles on n X n+1 square grid of points. %H A222200 Peter Tittmann, <a href="http://www.htwm.de/~peter/research/enumeration.html">Enumeration in graphs: counting Hamiltonian cycles</a> [Broken link?] %H A222200 Peter Tittman, <a href="/A222200/a222200.jpg">Illustration of a(4) = 14</a> [Taken from preceding link] %H A222200 Peter Tittmann, <a href="http://web.archive.org/web/20101127064650/https://www.staff.hs-mittweida.de/~peter/research/enumeration.html">Enumeration in graphs: counting Hamiltonian cycles</a> [Backup copy of top page only, on the Internet Archive] %H A222200 <a href="/index/Gra#graphs">Index entries for sequences related to graphs, Hamiltonian</a> %F A222200 a(n) = A321172(n,n+1) = A321172(n+1,n). - _Robert FERREOL_, Apr 01 2019 %Y A222200 Cf. A003763, A321172. %K A222200 nonn %O A222200 2,2 %A A222200 _N. J. A. Sloane_, Feb 14 2013 %E A222200 a(16) from _Huaide Cheng_, Jul 02 2025