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 A270246 #18 Feb 16 2025 08:33:31 %S A270246 1,2,2,4,7,4,7,32,32,7,11,108,370,108,11,18,342,2764,2764,342,18,29, %T A270246 1104,19874,41025,19874,1104,29,47,3544,144108,576287,576287,144108, %U A270246 3544,47,76,11396,1043060,8205424,15637256,8205424,1043060,11396,76 %N A270246 Array read by antidiagonals: T(n,m) is the number of matchings in the torus grid graph C_n X C_m. %H A270246 Andrew Howroyd, <a href="/A270246/b270246.txt">Table of n, a(n) for n = 1..284</a> %H A270246 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IndependentEdgeSet.html">Independent Edge Set</a> %H A270246 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Matching.html">Matching</a> %H A270246 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TorusGridGraph.html">Torus Grid Graph</a> %F A270246 T(1, m) = A000032(m) for m<>2. %e A270246 The start of the sequence as table: %e A270246 * 1 2 4 7 11 18 ... %e A270246 * 2 7 32 108 342 1104 ... %e A270246 * 4 32 370 2764 19874 144108 ... %e A270246 * 7 108 2764 41025 576287 8205424 ... %e A270246 * 11 342 19874 576287 15637256 430996378 ... %e A270246 * 18 1104 144108 8205424 430996378 23079663560 ... %e A270246 * ... %Y A270246 Main diagonal is A270247. Row 2 is A102080. %K A270246 nonn,tabl %O A270246 1,2 %A A270246 _Andrew Howroyd_, Mar 13 2016