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%I #16 Jan 13 2021 01:20:22
%S 1,2,28,696,26512,1402656,97017792,8418174848,889241719040,
%T 111774837350912,16420543334734848,2778708477919836160,
%U 535183812199464341504,116142946557502449852416,28156854547845767203373056,7569375509914847295271043072,2241898693518356603925445017600
%N Consider the family of directed multigraphs enriched by the species of parts. Sequence gives number of those multigraphs with n labeled arcs.
%D G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004.
%H Andrew Howroyd, <a href="/A098631/b098631.txt">Table of n, a(n) for n = 0..100</a>
%H 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 a(n) = 2^n*A020556(n). - _Vladeta Jovovic_, Aug 11 2005
%F E.g.f.: B(R(x)) where B(x) is the e.g.f. of A014505 and 1 + R(x) is the e.g.f. of A000079. - _Andrew Howroyd_, Jan 12 2021
%o (PARI) \\ R(n) is A000079 as e.g.f.; EnrichedGdSeq defined in A098623.
%o R(n)={exp(2*x + O(x*x^n))}
%o EnrichedGdSeq(R(20)) \\ _Andrew Howroyd_, Jan 12 2021
%Y Cf. A000079, A014505, A020556, A098623, A098628, A098629, A098630.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Oct 26 2004
%E More terms from _Vladeta Jovovic_, Aug 11 2005
%E Terms a(14) and beyond from _Andrew Howroyd_, Jan 12 2021
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