OFFSET
0,3
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]
FORMULA
a(n) = Sum_{k=0..n} (-1)^(n-k) * Stirling1(n, k) * A020556(k). - Sean A. Irvine, Apr 24 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Gilbert Labelle (gilbert(AT)lacim.uqam.ca), Simon Plouffe
STATUS
approved