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 A322140 #8 Nov 30 2018 14:40:23
%S A322140 1,1,1,2,7,37,262,2312,24338,296928,4112957,63692909,1089526922,
%T A322140 20389411551,414146189901,9070116944468,212983762029683,
%U A322140 5336570227705763,142083405456873290,4004953714929148655,119128974685786590410,3728639072095285867881
%N A322140 Number of labeled 2-connected multigraphs with n edges (the vertices are {1,2,...,k} for some k).
%C A322140 We consider a single edge to be 2-connected, so a(1) = 1.
%H A322140 Andrew Howroyd, <a href="/A322140/b322140.txt">Table of n, a(n) for n = 0..100</a>
%H A322140 Gus Wiseman, <a href="/A322140/a322140.png">The a(5) = 37 labeled 2-connected multigraphs with 5 edges.</a>
%o A322140 (PARI) seq(n)={Vec(1 + vecsum(Vec(serlaplace(log(x/serreverse(x*deriv(log(sum(k=0, n, 1/(1 - y + O(y*y^n))^binomial(k, 2) * x^k / k!) + O(x*x^n)))))))))} \\ _Andrew Howroyd_, Nov 29 2018
%Y A322140 Cf. A002218, A002905, A013922, A275307, A291841, A304118, A304887, A322110, A322117, A322118, A322137, A322138.
%K A322140 nonn
%O A322140 0,4
%A A322140 _Gus Wiseman_, Nov 27 2018
%E A322140 Terms a(7) and beyond from _Andrew Howroyd_, Nov 29 2018