A057272 Triangle T(n,k) of number of digraphs with a quasi-source on n labeled nodes and with k arcs, k=0,1,..,n*(n-1).

1, 0, 2, 1, 0, 0, 12, 20, 15, 6, 1, 0, 0, 0, 104, 426, 768, 920, 792, 495, 220, 66, 12, 1, 0, 0, 0, 0, 1160, 9184, 32420, 73000, 123425, 166860, 184426, 167900, 125965, 77520, 38760, 15504, 4845, 1140, 190, 20, 1

Offset

1,3

Links

Table of n, a(n) for n=1..45.

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

Example

Triangle starts:
1;
0,2,1;
0,0,12,20,15,6,1;
0,0,0,104,426,768,920,792,495,220,66,12,1;
...
Number of digraphs with a quasi-source on 3 labeled nodes is 54=12+20+15+6+1.

Crossrefs

Row sums give A049414. Cf. A057270, A057271, A057273-A057279.

Sequence in context: A201299 A057274 A088632 * A062735 A054547 A202717

Adjacent sequences: A057269 A057270 A057271 * A057273 A057274 A057275

Keyword

nonn,tabf

Author

Vladeta Jovovic, Goran Kilibarda, Sep 14 2000

Status

approved