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 A367436 #7 Nov 18 2023 13:21:49 %S A367436 1,1,0,2,4080 %N A367436 Number of Hamiltonian cycles in the polyomino graph PG(n) defined in A367435. %C A367436 A cycle and its reverse are not both counted. %C A367436 We follow the convention in A003216 that the complete graphs on 1 and 2 nodes have 1 and 0 Hamiltonian cycles, respectively, so that a(1) = a(2) = 1 and a(3) = 0, but it could also be argued that a(1) = a(2) = 0 and/or a(3) = 1. %H A367436 Pontus von Brömssen, <a href="/A367436/a367436.svg">A Hamiltonian cycle in the heptomino graph</a>. %H A367436 Pontus von Brömssen, <a href="/A367123/a367123.svg">A Hamiltonian cycle in the hexomino graph</a>. %H A367436 MathOverflow, <a href="https://mathoverflow.net/questions/355220">Generating all pentominoes by cutting and pasting</a>. %H A367436 <a href="/index/Pol#polyominoes">Index entries for sequences related to polyominoes</a>. %F A367436 a(n) <= A367123(n). %F A367436 a(n) > 0 for 4 <= n <= 13. %Y A367436 Cf. A003216, A367123, A367435. %K A367436 nonn,more %O A367436 1,4 %A A367436 _Pontus von Brömssen_, Nov 18 2023