A049414 Number of quasi-initially connected digraphs with n labeled nodes.

1, 3, 54, 3804, 1022320, 1065957628, 4389587378792, 72020744942708040, 4721708591209396542528, 1237892622263984613044109216, 1298060581376190776821670648395840

Offset

1,2

Comments

We say that a node v of a digraph is a quasi-source iff for every other node u there exists directed path from u to v or from v to u. A digraph with at least one quasi-source is called quasi-initially connected.

Links

Table of n, a(n) for n=1..11.

Sean A. Irvine, Java program (github)

V. Jovovic and G. Kilibarda, Enumeration of labeled quasi-initially connected digraphs, Discrete Math., 224 (2000), 151-163.

Formula

The recurrence formulas are too long to be presented here.

Crossrefs

Cf. A003027, A003028, A003029, A003030.

Row sums of A057272.

Sequence in context: A091796 A171213 A006025 * A003027 A054545 A158103

Adjacent sequences: A049411 A049412 A049413 * A049415 A049416 A049417

Keyword

nonn

Author

Vladeta Jovovic, Goran Kilibarda

Status

approved