A121936 - OEIS

This site is supported by donations to The OEIS Foundation.

A121936

Number of digraphs with labeled vertices and labeled arcs, with n arcs and with no vertex of indegree 0 or outdegree 0.

1, 0, 2, 18, 518, 23610, 1600982, 150451098, 18694217558, 2966151496410, 584994048653462, 140357794553191578, 40253455215544778198, 13598018000464234802010, 5343837921922909297592342 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,3`
	FORMULA	`E.g.f.: Sum(Sum((-1)^(n-k)binomial(n,k)(exp((k-1)x)-1)^k(exp(k*x)-1)^(n-k),k=0..n),n=0..infinity).`
	CROSSREFS	`Cf. A122399, A122418.` `Sequence in context: A156907 A053916 A015203 * A063389 A188202 A071352` `Adjacent sequences: A121933 A121934 A121935 * A121937 A121938 A121939`
	KEYWORD	`easy,nonn`
	AUTHOR	`Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 03 2006`
	EXTENSIONS	`More terms from Max Alekseyev (maxale(AT)gmail.com), Jul 29 2009`

Content is available under The OEIS End-User License Agreement .

Last modified February 15 12:05 EST 2012. Contains 205782 sequences.