A139627 Number of strongly connected directed multigraphs with loops allowed and with n arcs.

1, 1, 2, 4, 12, 37, 162, 738, 3928, 22436, 138716, 911529, 6339770, 46336941, 354453138, 2826472249, 23423053967, 201179882629, 1786791372857, 16377359709120, 154644691266520, 1502016160624186, 14985219655673207, 153377735526218010, 1608741204839374373

Offset: 0

Author

Benoit Jubin, May 01 2008

Keywords

• nonn

Comments

The term a(0)=1 can be interpreted as either a singleton vertex or the graph with no vertices. - Andrew Howroyd, Jan 14 2022

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..40

Crossrefs

Row sums of A139622.

Cf. A052171, A350489, A350752.

Programs

PARI

\\ See PARI link in A350489 for program code.
A139627seq(20) \\ Andrew Howroyd, Jan 14 2022

Extensions

3 more terms from R. J. Mathar, Aug 04 2017

Terms a(7) and beyond from Andrew Howroyd, Jan 14 2022