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 A286187 #32 Feb 16 2025 08:33:44
%S A286187 6,33,188,985,4990,24645,119712,574225,2727218,12847821,60115060,
%T A286187 279652793,1294441894,5965567125,27387631368,125308264225,
%U A286187 571591760602,2600204421405,11799376912220,53424388364873,241398575303374,1088727972172389,4901842528232304,22034981672761649
%N A286187 Number of connected induced (non-null) subgraphs of the web graph with 3n nodes.
%H A286187 Andrew Howroyd, <a href="/A286187/b286187.txt">Table of n, a(n) for n = 1..200</a>
%H A286187 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Vertex-InducedSubgraph.html">Vertex-Induced Subgraph</a>
%H A286187 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/WebGraph.html">Web Graph</a>
%F A286187 Empirical g.f.: x*(6 - 39*x + 92*x^2 - 101*x^3 + 32*x^4 - 8*x^5 + 64*x^6 - 48*x^7) / ((1 - x)^2*(1 - 5*x + 2*x^2 + 4*x^3)^2). - _Colin Barker_, May 21 2017
%t A286187 {6, 33} ~Join~ Table[g = GraphData[{"Web", n}]; -1 + ParallelSum[Boole@ ConnectedGraphQ@ Subgraph[g, s], {s, Subsets@ Range[3 n]}], {n, 3, 6}]
%Y A286187 Cf. A020873 (wheel), A059020 (ladder), A059525 (grid), A286139 (king), A286182 (prism), A286183 (antiprism), A286184 (helm), A286185 (Möbius ladder), A286186 (friendship), A286188 (gear), A286189 (rook), A285765 (queen).
%K A286187 nonn
%O A286187 1,1
%A A286187 _Giovanni Resta_, May 04 2017
%E A286187 a(12)-a(24) from _Andrew Howroyd_, May 20 2017