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 A270228 #25 Feb 16 2025 08:33:31 %S A270228 1,7,370,270529,3337807996,855404716021831,5352265402523357926168, %T A270228 940288991338542314571521981185, %U A270228 5236753179470435264288904589157765055760,1029720447530443779943631183186535523331685533812231 %N A270228 Number of matchings in the n X n rook graph K_n X K_n. %C A270228 K_n X K_n is also called the rook graph or lattice graph. %H A270228 Andrew Howroyd, <a href="/A270228/b270228.txt">Table of n, a(n) for n = 1..16</a> %H A270228 Andrew Howroyd, <a href="/A270228/a270228.cs.txt">C# software related to this sequence</a> %H A270228 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IndependentEdgeSet.html">Independent Edge Set</a> %H A270228 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Matching.html">Matching</a> %H A270228 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RookGraph.html">Rook Graph</a> %H A270228 Wikipedia, <a href="https://en.wikipedia.org/wiki/Rook%27s_graph">Rook's graph</a>, <a href="https://en.wikipedia.org/wiki/Hosoya_index">Hosoya index</a> %Y A270228 Cf. A270227, A270229, A085537 (Wiener index), A002720 (independent vertex sets), A269561, A028420. %K A270228 nonn %O A270228 1,2 %A A270228 _Andrew Howroyd_, Mar 13 2016