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 A270273 #21 Feb 16 2025 08:33:31 %S A270273 0,0,0,1,1,1,1,3,3,1,1,6,48,6,1,1,5,126,126,5,1,1,8,390,1344,390,8,1, %T A270273 1,7,1014,2930,2930,1014,7,1,1,10,2982,28060,23580,28060,2982,10,1,1, %U A270273 9,8094,55230,145210,145210,55230,8094,9,1 %N A270273 Array read by antidiagonals: T(n,m) = number of Hamiltonian cycles in C_n X C_m. %H A270273 Andrew Howroyd, <a href="/A270273/b270273.txt">Table of n, a(n) for n = 1..191</a> %H A270273 Artem M. Karavaev, <a href="https://web.archive.org/web/20161024010518/http://flowproblem.ru/cycles/hamilton-cycles">Hamilton Cycles</a> %H A270273 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HamiltonianCycle.html">Hamiltonian Cycle</a> %H A270273 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TorusGridGraph.html">Torus Grid Graph</a> %F A270273 T(n,2) = A124349(n) / 2. %e A270273 The start of the sequence as table: %e A270273 0 0 1 1 1 1 1 ... %e A270273 0 1 3 6 5 8 7 ... %e A270273 1 3 48 126 390 1014 2982 ... %e A270273 1 6 126 1344 2930 28060 55230 ... %e A270273 1 5 390 2930 23580 145210 1045940 ... %e A270273 1 8 1014 28060 145210 3273360 16111928 ... %e A270273 1 7 2982 55230 1045940 16111928 257165468 ... %e A270273 ... %Y A270273 Row n=3-5 give: A194952, A216588, A358853. %Y A270273 Main diagonal gives A222199. %K A270273 nonn,tabl %O A270273 1,8 %A A270273 _Andrew Howroyd_, Mar 14 2016