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 A320489 #10 Jan 26 2020 16:28:21 %S A320489 1,2,6,40,581,17954,1376484,275524246,147627941386,213261119287108, %T A320489 836129127802137203,8961301472286672235092, %U A320489 264386586050074867407985650,21609889100291959988235675761782,4921292113269596022145447106163528469,3138303995382684496665239674427115214538716 %N A320489 Number of connected nets on n unlabeled nodes. %H A320489 Andrew Howroyd, <a href="/A320489/b320489.txt">Table of n, a(n) for n = 0..50</a> %H A320489 Edward A. Bender and E. Rodney Canfield, <a href="https://doi.org/10.1016/0095-8956(83)90040-0">Enumeration of connected invariant graphs</a>, Journal of Combinatorial Theory, Series B 34.3 (1983): 268-278. See p. 274. %H A320489 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %F A320489 EULERi transform of A004103. %Y A320489 Cf. A004103. %K A320489 nonn %O A320489 0,2 %A A320489 _N. J. A. Sloane_, Oct 25 2018 %E A320489 a(0)=1 prepended by _Andrew Howroyd_, Jan 26 2020