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 A053517 #8 Nov 07 2019 19:24:37 %S A053517 1,5,132,22662,29174514,286151774704,21712410740238954, %T A053517 12980058344488389640470,62082372574276838787463958455, %U A053517 2405193558246444686967534052419452898,762399004073792344564641131264446658930745417 %N A053517 Number of connected directed 2-multigraphs on n nodes. %C A053517 A 2-multigraph is similar to an ordinary graph except there are 0, 1 or 2 edges between any two nodes (self-loops are not allowed). %H A053517 Andrew Howroyd, <a href="/A053517/b053517.txt">Table of n, a(n) for n = 1..40</a> %F A053517 Inverse Euler transform of A053467. %Y A053517 Cf. A053467. %K A053517 easy,nonn %O A053517 1,2 %A A053517 _Vladeta Jovovic_, Jan 14 2000 %E A053517 a(11) from _Andrew Howroyd_, Nov 07 2019