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 A238817 #13 Jun 30 2023 12:20:37 %S A238817 1,2,28,1504,520176,696179102,5373177281748,166903679914150336, %T A238817 28636599794306124116062,20262965974179958448766775754 %N A238817 Number of Hamiltonian cycles on 2n X 2n grid with at least 180-degree rotational symmetry. %H A238817 Ed Wynn, <a href="http://arxiv.org/abs/1402.0545">Enumeration of nonisomorphic Hamiltonian cycles on square grid graphs</a>, arXiv preprint arXiv:1402.0545 [math.CO], 2014. %Y A238817 Cf. A003763. %K A238817 nonn,more %O A238817 1,2 %A A238817 _N. J. A. Sloane_, Mar 05 2014