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 A098630 #17 Jul 22 2025 05:57:57
%S A098630 1,4,60,1624,66240,3711200,269670208,24435113216,2682916389632,
%T A098630 349223324753408,52965538033020928,9229753832340117504,
%U A098630 1826647528631522463744,406579171521484851396608,100934277604965329345822720,27746271707522968205726416896
%N A098630 Consider the family of directed multigraphs enriched by the species of parts. Sequence gives number of those multigraphs with n labeled loops and arcs.
%D A098630 G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004.
%H A098630 Andrew Howroyd, <a href="/A098630/b098630.txt">Table of n, a(n) for n = 0..100</a>
%H A098630 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 A098630 a(n) = 2^n*Bell(2*n). - _Vladeta Jovovic_, Aug 22 2006
%F A098630 E.g.f.: B(R(x)) where B(x) is the e.g.f. of A014507 and 1 + R(x) is the e.g.f. of A000079. - _Andrew Howroyd_, Jan 12 2021
%o A098630 (PARI) a(n) = {2^n*sum(k=0, 2*n, stirling(2*n,k,2))} \\ _Andrew Howroyd_, Jan 12 2021
%o A098630 (PARI) \\ R(n) is A000079 as e.g.f.; EnrichedGdlSeq defined in A098622.
%o A098630 R(n)={exp(2*x + O(x*x^n))}
%o A098630 EnrichedGdlSeq(R(20)) \\ _Andrew Howroyd_, Jan 12 2021
%Y A098630 Cf. A000079, A014507, A098622, A098628, A098629, A098631.
%K A098630 nonn
%O A098630 0,2
%A A098630 _N. J. A. Sloane_, Oct 26 2004
%E A098630 Terms a(11) and beyond from _Andrew Howroyd_, Jan 12 2021