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 A112675 #22 Feb 16 2025 08:32:59 %S A112675 1,6,24,228,3936,132624,8762040,1156532424,306700450536, %T A112675 164818597404924,180360080611682424,403600060221250880496, %U A112675 1853096813379189131728692,17504763708306471241857275208 %N A112675 Number of directed Hamiltonian paths on a triangular grid, n vertices on each side. %C A112675 This sequence counts paths in a triangular region of the familiar 2-dimensional lattice in which each point has 6 neighbors (sometimes called either the "triangular" or the "hexagonal" lattice), visiting every vertex of the region exactly once. The paths are not assumed to be closed. A path and its reversal are not considered equivalent. %H A112675 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianPath.html">Hamiltonian Path</a> %H A112675 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularGridGraph.html">Triangular Grid Graph</a> %H A112675 <a href="/index/Gra#graphs">Index entries for sequences related to graphs, Hamiltonian</a> %Y A112675 Cf. A003763, A112676. %K A112675 more,nonn %O A112675 1,2 %A A112675 _Gareth McCaughan_, Dec 30 2005 %E A112675 a(8)-a(14) from _Andrew Howroyd_, Nov 02 2015