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 A371869 #9 Apr 12 2024 07:50:01 %S A371869 0,0,0,1,1,4,6,26,74,356,1655,9750,62009,448498,3554505,31000909, %T A371869 294772655,3047952802,34135465140 %N A371869 Number of 2-connected chordal bipartite graphs on n unlabeled vertices. %C A371869 A chordal bipartite graph is a bipartite graph with no induced cycles longer than 4-cycles. Note that this is not the same as a bipartite graph which is chordal, as that would exclude all cycles. %H A371869 Brendan McKay, <a href="https://users.cecs.anu.edu.au/~bdm/nauty/">nauty software</a> that can generate these graphs. %H A371869 Wikipedia, <a href="https://en.wikipedia.org/wiki/Chordal_bipartite_graph">Chordal bipartite graph</a>. %e A371869 For n=4, the only example is the 4-cycle. For n=5, the only example is K(2,3). %Y A371869 Cf. A371867, A371868. %K A371869 nonn,hard,more %O A371869 1,6 %A A371869 _Brendan McKay_, Apr 09 2024