

A049512


Number of quasiinitially connected digraphs on n unlabeled nodes.


4




OFFSET

1,2


COMMENTS

From Sean A. Irvine, Aug 01 2021: (Start)
A quasiinitially connected digraph is a digraph containing at least one vertex v such that every vertex u in the graph can either be reached from v or v can be reached from u (while obeying the directions on the edges).
There is no known formula. (End)


LINKS

Table of n, a(n) for n=1..7.
Sean A. Irvine, Java program (github)
V. Jovovic and G. Kilibarda, Enumeration of labeled quasiinitially connected digraphs, Discrete Math., 224 (2000), 151163.


CROSSREFS

Cf. A049414, A003085, A035512, A003088, A051421.
Sequence in context: A323209 A239994 A242007 * A003507 A338979 A307066
Adjacent sequences: A049509 A049510 A049511 * A049513 A049514 A049515


KEYWORD

hard,more,nonn


AUTHOR

Vladeta Jovovic, Goran Kilibarda


EXTENSIONS

a(6)a(7) from Sean A. Irvine, Aug 01 2021


STATUS

approved



