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 A003515 M4009 #23 Jan 24 2020 19:17:07
%S A003515 0,1,1,0,5,51,3634,374119,73161880,26545249985,17904840957826,
%T A003515 22602069719494379,53938857227326533032,246107945479472758874483,
%U A003515 2170331943503938546383205218,37340982087637629911717846092591,1262915556964772342158139988356979872
%N A003515 Number of series-reduced connected labeled graphs with n nodes.
%C A003515 Jackson and Reilly paper has typographical error in value for a(12). - _Sean A. Irvine_, Jun 17 2015
%D A003515 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A003515 Andrew Howroyd, <a href="/A003515/b003515.txt">Table of n, a(n) for n = 0..50</a> (terms 0..34 from Sean A. Irvine)
%H A003515 D. M. Jackson and J. W. Reilly, <a href="https://doi.org/10.1016/0095-8956(75)90090-8">The enumeration of homeomorphically irreducible labeled graphs</a>, J. Combin. Theory, B 19 (1975), 272-286.
%F A003515 E.g.f.: log(B(x)) where B(x) is the e.g.f. for A003514. - _Sean A. Irvine_, Jun 17 2015
%o A003515 (PARI) \\ See Jackson & Reilly for e.g.f.
%o A003515 seq(n)={my(A=O(x*x^n)); Vec(serlaplace(log((exp(x/2 - x^2/4 + A)/sqrt(1 + x + A))*sum(k=0, n, (2*exp(-x/(1+x) + A))^binomial(k,2) * (x*exp((x^2 + A)/(2*(1 + x))))^k / k!))), -(n+1))} \\ _Andrew Howroyd_, Jan 24 2020
%Y A003515 Row sums of A331438.
%Y A003515 Column sums of A331437.
%Y A003515 Cf. A003514, A331584.
%K A003515 nonn
%O A003515 0,5
%A A003515 _N. J. A. Sloane_
%E A003515 More terms and a(12) corrected by _Sean A. Irvine_, Jun 17 2015