A139624 - OEIS

A139624

Table read by rows: T(n,k) is the number of connected directed multigraphs with loops and no vertex of degree 0, with n arcs and k vertices, which are transitive (the existence of a path between two points implies the existence of an arc between those two points).

%I #13 Feb 07 2023 08:15:20

%S 1,1,1,3,2,1,6,7,3,1,11

%N Table read by rows: T(n,k) is the number of connected directed multigraphs with loops and no vertex of degree 0, with n arcs and k vertices, which are transitive (the existence of a path between two points implies the existence of an arc between those two points).

%C Length of the n-th row: n+1.

%C T(n,1) = 1

%C Row sums: A139629.

%e Triangle begins

%e 1;

%e 1, 1;

%e 3, 2, 1;

%e 6, 7, 3, 1;

%Y Cf. A139623, A139625.

%K nonn,tabl,more

%O 1,4

%A _Benoit Jubin_, May 01 2008