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 A332651 #10 Dec 23 2020 01:51:45
%S A332651 1,1,0,0,1,0,1,1,1,1,4,2,7,9,14,26,48,71,154,243,478,894,1631,3149,
%T A332651 6062,11295,22469,42900,83528,164829,321012,632960,1255613,2472803,
%U A332651 4928140,9808439,19533534,39134059,78345317,157177556,316398963,636790282,1284910954
%N A332651 Number of polygonal cacti on n unlabeled nodes with every polygon having an even number of edges.
%C A332651 Bridges are disallowed.
%H A332651 Andrew Howroyd, <a href="/A332651/b332651.txt">Table of n, a(n) for n = 0..200</a>
%H A332651 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cactus_graph">Cactus graph</a>
%H A332651 <a href="/index/Ca#cacti">Index entries for sequences related to cacti</a>
%e A332651 a(6) = 1 corresponding with a hexagon.
%e A332651 a(7) = 1 corresponding with two quadrilaterals joined at a node.
%o A332651 (PARI) \\ See A332650 for UCacti.
%o A332651 seq(n)={concat([1], UCacti(vector(n, i, i>2&&i%2==0)))}
%Y A332651 Cf. A000083, A035085, A091487, A332649, A332650.
%K A332651 nonn
%O A332651 0,11
%A A332651 _Andrew Howroyd_, Feb 18 2020