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 A381468 #8 Feb 25 2025 01:57:14 %S A381468 1,1,1,2,4,8,20,48,133,374,1124,3439,10923,35245,116128,387729, %T A381468 1312038,4485906,15486546,53900520,188998450,667062919,2368440477, %U A381468 8454560144,30328595227,109285433191,395425965732,1436219868659,5234881134074,19143123415166,70216752517419 %N A381468 Number of simple connected graphs on n unlabeled nodes with no node a member of more than one cycle. %C A381468 All such graphs are cactus graphs (with bridges allowed). %H A381468 Andrew Howroyd, <a href="/A381468/b381468.txt">Table of n, a(n) for n = 0..1000</a> %H A381468 R. J. Mathar, <a href="http://arxiv.org/abs/1808.06264">Counting connected graphs without overlapping cycles</a>, arXiv:1808.06264 [math.CO] (2018). %H A381468 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cactus_graph">Cactus graph</a>. %H A381468 <a href="/index/Ca#cacti">Index entries for sequences related to cacti</a>. %o A381468 (PARI) Vec(G(31,1)) \\ G() defined in A381467. %Y A381468 Row sums of A381467. %Y A381468 Cf. A000083, A317722 (with 2-cycles), A380632, A380805. %K A381468 nonn %O A381468 0,4 %A A381468 _Andrew Howroyd_, Feb 24 2025