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 A340029 #11 Jan 09 2021 22:11:28
%S A340029 0,1,1,6,37,388,6004,148759,5974184,404509191,47552739892,
%T A340029 9923861406343,3735194287263442,2565376853616300801,
%U A340029 3244070698095148283628,7607050619214875184974489,33269229977451262849539412860,272689940536978851416633440863567
%N A340029 Number of unlabeled 2-connected graphs with n vertices rooted at a pair of indistinguishable vertices.
%H A340029 Andrew Howroyd, <a href="/A340029/b340029.txt">Table of n, a(n) for n = 1..30</a>
%o A340029 (PARI) \\ See A004115 for graphsSeries and A339645 for combinatorial species functions.
%o A340029 blockGraphs(n)={my(gc=sLog(graphsSeries(n)), gcr=sPoint(gc)); intformal(x*sSolve( sLog( gcr/(x*sv(1)) ), gcr ), sv(1)) + sSolve(subst(gc, sv(1), 0), gcr)}
%o A340029 cycleIndexSeries(n)={sCartProd(blockGraphs(n), x^2 * symGroupCycleIndex(2) * symGroupSeries(n-2))}
%o A340029 { my(N=15); Vec(OgfSeries(cycleIndexSeries(N)), -N) }
%Y A340029 Cf. A002218, A004115, A241768, A303829, A303831, A340028.
%K A340029 nonn
%O A340029 1,4
%A A340029 _Andrew Howroyd_, Jan 02 2021