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 A122801 #8 Nov 09 2019 11:41:27
%S A122801 1,1,21,2650,1452605,3149738046,26503552820514,868081172737564500,
%T A122801 111606080497500509325405,56762846667123360827351083510,
%U A122801 114847831981827229530824587617895286,927685362544629192461621864598358779955500,29976424929810726580224613882836823991388901138994
%N A122801 Number of labeled bipartite graphs on 2n vertices having equal parts and no isolated vertices.
%H A122801 Andrew Howroyd, <a href="/A122801/b122801.txt">Table of n, a(n) for n = 0..50</a>
%F A122801 For n>0, a(n) = A001700(n-1) * A048291(n) = A052332(2n) - A122802(2n).
%o A122801 (PARI) { A122801(n) = binomial(2*n-1,n) * sum(k=0, n, binomial(n, k) * (-1)^k * (2^(n-k)-1)^n ); }
%Y A122801 Cf. A122802, A048291, A052332, A001831, A002031, A047863, A001700.
%K A122801 nonn
%O A122801 0,3
%A A122801 _Max Alekseyev_, Sep 11 2006
%E A122801 Terms a(11) and beyond from _Andrew Howroyd_, Nov 07 2019