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 A244511 #17 Aug 13 2020 14:02:28 %S A244511 0,1,2,3,4,5,6,7,8,9,10,11,12,14,15,16,17,18,19,20,22,23,24,26,27,28, %T A244511 30,32,33,34,36,38,40,45,48,52,60,62,70,72,76,80,90,108,120,144,168, %U A244511 240,360 %N A244511 Possible numbers of Hamiltonian cycles up to direction in 7-vertex graphs. %H A244511 Erich Friedman, <a href="https://erich-friedman.github.io/mathmagic/0912.html">Math Magic</a> (September 2012) %e A244511 The empty graph on 7 vertices has no Hamiltonian cycles, so a(1) = 0. The cycle graph C_7 has exactly one so a(2) = 1. %Y A244511 Cf. A249905 (for the definition of "up to direction"), A249906, A253648 (numbers of Hamiltonian cycles that are not possible in 8-vertex graphs), A305190. %K A244511 nonn,fini,full %O A244511 1,3 %A A244511 _Jeremy Tan_, Nov 11 2014