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 A238819 #20 Jun 30 2023 12:22:57 %S A238819 1,2,204,510718,31008619522,43911490791183200, %T A238819 1424639466911800364132674,1048492580133908850434091619741314 %N A238819 Number of Hamiltonian cycles on 4n+2 X 4n+2 grid with at least 90-degree rotational symmetry. %H A238819 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 A238819 Cf. A003763. %K A238819 nonn,more %O A238819 0,2 %A A238819 _N. J. A. Sloane_, Mar 05 2014 %E A238819 a(5)-a(7) from _Andrew Howroyd_, Apr 06 2016