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 A238818 #15 Jun 30 2023 12:21:27 %S A238818 1,2,6,40,488,13782,757626,95835196,24236840344,13996574799274 %N A238818 Number of Hamiltonian cycles on 2n X 2n grid with at least the symmetries of two reflections and 180-degree rotation. %H A238818 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 A238818 Cf. A003763. %K A238818 nonn,more %O A238818 1,2 %A A238818 _N. J. A. Sloane_, Mar 05 2014