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 A020564 #25 Apr 28 2019 11:39:51
%S A020564 1,1,7,88,1686,44746,1550780,67381560,3562868722,224113484498,
%T A020564 16473080538422,1394549071911392,134354292707375708,
%U A020564 14583554691197056644,1768268298908733087440,237735747822259634293456,35212913676142942896961116
%N A020564 Number of cyclic oriented multigraphs on n labeled arcs (without loops).
%H A020564 G. Labelle, <a href="https://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 A020564 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 A020564 a(n) = Sum_{k=0..n} (-1)^(n-k)*Stirling1(n, k)*A014505(k). - _Sean A. Irvine_, Apr 25 2019
%Y A020564 Cf. A008275 (Stirling1), A014505.
%K A020564 nonn
%O A020564 0,3
%A A020564 Gilbert Labelle (gilbert(AT)lacim.uqam.ca), _Simon Plouffe_