%I #22 Feb 16 2025 08:33:53
%S 1,4,56,3900,16015496,140897335664,4437432714568987812822
%N Number of (undirected) Hamiltonian cycles in the n-polygon diagonal intersection graph.
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a>
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PolygonDiagonalIntersectionGraph.html">Polygon Diagonal Intersection Graph</a>
%Y Cf. A294992, A300525, A300551.
%K nonn,more,changed
%O 3,2
%A _Eric W. Weisstein_, Mar 08 2018
%E a(8)-a(9) from _Andrew Howroyd_, Mar 11 2018