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 A056988 #13 Feb 16 2025 08:32:43 %S A056988 0,1,8,116,4316,483835,175048780,212125583518,887136857205696, %T A056988 13086449050056880074,691487226135525983266460, %U A056988 132437909864451274070001431956,92821692762628588679459049647697100,239928160288841627346208269001938306502290 %N A056988 Number of weakly connected digraphs on n unlabeled nodes that are not strongly connected. %H A056988 Andrew Howroyd, <a href="/A056988/b056988.txt">Table of n, a(n) for n = 1..50</a> %H A056988 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ConnectedDigraph.html">Connected Digraph.</a> %F A056988 a(n) = A003085(n) - A035512(n). %Y A056988 Cf. A003085, A035512. %K A056988 nonn %O A056988 1,3 %A A056988 _Eric W. Weisstein_ %E A056988 a(12)-a(14) added by _Andrew Howroyd_, Dec 27 2021