%I #21 Apr 24 2019 05:32:51

%S 1,1,8,110,2262,63822,2335856,106643980,5901564892,387251339836,

%T 29612207398688,2601877956513640,259646660158526856,

%U 29140784853464966632,3647614440065070983488,505553321559685235600720,77096697572750991426551056,12864789849511242132008021520

%N Number of ordered oriented multigraphs on n labeled arcs (without loops).

%H 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 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) = Sum_{k=0..n} (-1)^(n-k) * Stirling1(n, k) * A020556(k). - _Sean A. Irvine_, Apr 24 2019

%Y Cf. A020556.

%K nonn

%O 0,3

%A Gilbert Labelle (gilbert(AT)lacim.uqam.ca), _Simon Plouffe_