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 A341503 #7 Mar 14 2021 18:44:01 %S A341503 1,10,193,5950,270529,16873930,1384880065,144218696590,18583827550465, %T A341503 2898418007316970,538034003700151105,117117180185558050750, %U A341503 29538673951318735414465,8540274169019607609510250,2805241403079208727201012545,1038436904586470317663800172750 %N A341503 Number of matchings in the 4 X n rook graph. %H A341503 Andrew Howroyd, <a href="/A341503/b341503.txt">Table of n, a(n) for n = 0..50</a> %e A341503 The a(1) = 10 matchings consist of the empty matching, 6 matchings with a single edge and 3 perfect matchings. %Y A341503 Row 4 of A270227. %K A341503 nonn %O A341503 0,2 %A A341503 _Andrew Howroyd_, Feb 21 2021