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 A361245 #8 Mar 11 2023 00:13:10 %S A361245 1,1,1,4,20,115,715,4683,31824,222300,1586310,11514030,84742320, %T A361245 630946446,4743789260,35965715780,274659794160,2110810059795, %U A361245 16312695488265,126693445737170,988340783454380,7740875273884445,60846920004855985,479854293574853085 %N A361245 Number of noncrossing 2,3 cacti with n nodes. %C A361245 A 2,3 cactus is a cactus composed of bridges and triangles. %H A361245 Andrew Howroyd, <a href="/A361245/b361245.txt">Table of n, a(n) for n = 0..500</a> %H A361245 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cactus_graph">Cactus graph</a>. %H A361245 <a href="/index/Ca#cacti">Index entries for sequences related to cacti</a>. %o A361245 (PARI) seq(n) = Vec(1 + x/(1 - serreverse((sqrt(1 + 4*x + O(x^n)) - 1)*(1 - x)^2/2))) %Y A361245 Cf. A091481, A091485, A091486, A091487, A361242, A361244. %K A361245 nonn %O A361245 0,4 %A A361245 _Andrew Howroyd_, Mar 08 2023