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 A014501 #30 Jul 08 2025 05:40:09 %S A014501 1,2,7,43,403,5245,89132,1898630,49209846,1517275859,54669946851, %T A014501 2269075206395,107199678164289,5707320919486026,339510756324234931, %U A014501 22400182888853554291,1628654713107465602783,129754625253841669625051 %N A014501 Number of graphs with loops, having unlabeled (non-isolated) nodes and n labeled edges. %D A014501 G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004. %H A014501 Andrew Howroyd, <a href="/A014501/b014501.txt">Table of n, a(n) for n = 0..200</a> %H A014501 G. Labelle, <a href="http://dx.doi.org/10.1016/S0012-365X(99)00265-4">Counting enriched multigraphs according to the number of their edges (or arcs)</a>, Discrete Math., 217 (2000), 237-248. %H A014501 G. Paquin, <a href="/A038205/a038205.pdf">Dénombrement de multigraphes enrichis</a>, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004. [Cached copy, with permission] %F A014501 E.g.f.: exp(-1+x/2)*Sum((1+x)^binomial(n+1, 2)/n!, n=0..infinity) [probably in the Labelle paper]. - _Vladeta Jovovic_, Apr 27 2004 %Y A014501 Row n=2 of A331161. %Y A014501 Cf. A020554, A020555, A014500. %K A014501 nonn %O A014501 0,2 %A A014501 _Simon Plouffe_, Gilbert Labelle (gilbert(AT)lacim.uqam.ca)