A020564 Number of cyclic oriented multigraphs on n labeled arcs (without loops).

1, 1, 7, 88, 1686, 44746, 1550780, 67381560, 3562868722, 224113484498, 16473080538422, 1394549071911392, 134354292707375708, 14583554691197056644, 1768268298908733087440, 237735747822259634293456, 35212913676142942896961116

Offset: 0

Author

Gilbert Labelle (gilbert(AT)lacim.uqam.ca), Simon Plouffe

Keywords

• nonn

Links

• G. Labelle, Counting enriched multigraphs according to the number of their edges (or arcs), Discrete Math., 217 (2000), 237-248.
• G. Paquin, Dénombrement de multigraphes enrichis, Mémoire, Math. Dept., Univ. Québec à Montréal, 2004. [Cached copy, with permission]

Crossrefs

Cf. A008275 (Stirling1), A014505.

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k)*Stirling1(n, k)*A014505(k). - Sean A. Irvine, Apr 25 2019