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 A306496 #52 Feb 16 2025 08:33:55 %S A306496 0,0,1,6,156,4800,208440,11939760,874681920,79795860480,8873760470400, %T A306496 1181869427692800,185755937440550400,34022680848982425600, %U A306496 7183771725162237004800,1732270657442505852672000,473131604733608510097408000,145308345869661566419795968000 %N A306496 Number of (undirected) Hamiltonian cycles in the n-crown graph. %H A306496 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CrownGraph.html">Crown Graph</a> %H A306496 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a> %F A306496 a(n) = A094047(n)/2. %Y A306496 Cf. A094047. %K A306496 nonn %O A306496 1,4 %A A306496 _Eric W. Weisstein_, May 06 2019