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 A073584 #10 Jul 14 2024 17:04:37 %S A073584 1,1,9,48,300,2520,22680,282240,3265920,43545600,618710400, %T A073584 10298534400,171243072000,3138418483200,61460695296000, %U A073584 1286751578112000,27743619391488000,640237370572800000,15448927751921664000,394130125324615680000,10422552203028725760000,288306186674956369920000 %N A073584 Commuting even permutations: number of ordered pairs g, h in the alternating group A_n such that gh = hg. %H A073584 N. J. A. Sloane, <a href="/A073584/b073584.txt">Table of n, a(n) for n = 1..37</a> %F A073584 For n>=2 : a(n) = (n!/2) * A000702(n). %Y A073584 Cf. A000702, A053529. %K A073584 nonn %O A073584 1,3 %A A073584 Yuval Dekel (dekelyuval(AT)hotmail.com), Sep 13 2003 %E A073584 More terms from _N. J. A. Sloane_ (based on A000702), Dec 31 2006