A057279 Triangle T(n,k) of number of digraphs with a quasi-source on n unlabeled nodes and with k arcs, k = 0..n*(n-1).

1, 0, 1, 1, 0, 0, 3, 4, 4, 1, 1, 0, 0, 0, 7, 21, 37, 47, 38, 27, 13, 5, 1, 1, 0, 0, 0, 0, 18, 90, 309, 661, 1125, 1477, 1665, 1489, 1154, 707, 379, 154, 61, 16, 5, 1, 1, 0, 0, 0, 0, 0, 44, 374, 1981, 7107, 19166, 41867, 77194, 122918, 170308, 206980, 220768, 207301, 171008, 124110, 78813, 43862, 21209, 8951, 3242, 1043, 288, 76, 17, 5, 1, 1

Offset: 1

Author

Vladeta Jovovic, Goran Kilibarda, Sep 14 2000

Keywords

• nonn
• tabf

Examples

			Table starts:
[1],
[0,1,1],
[0,0,3,4,4,1,1],
[0,0,0,7,21,37,47,38,27,13,5,1,1],
...
Number of digraphs with a quasi-source on 3 unlabeled nodes is 13=3+4+4+1+1.
		

Links

• Sean A. Irvine, Java program (github)
• V. Jovovic and G. Kilibarda, Enumeration of labeled quasi-initially connected digraphs, Discrete Math., 224 (2000), 151-163.

Crossrefs

Row sums give A049512. Cf. A057270-A057278.

Extensions

More terms from Sean A. Irvine, May 30 2022