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A057275 Triangle T(n,k) of number of unilaterally connected digraphs on n labeled nodes and with k arcs, k=0,1,..,n*(n-1). 2
1, 0, 2, 1, 0, 0, 6, 20, 15, 6, 1, 0, 0, 0, 24, 222, 660, 908, 792, 495, 220, 66, 12, 1, 0, 0, 0, 0, 120, 2304, 15540, 52700, 109545, 161120, 182946, 167660, 125945, 77520, 38760, 15504, 4845, 1140, 190, 20, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

EXAMPLE

[1],[0,2,1],[0,0,6,20,15,6,1],[0,0,0,0,24,222,660,908,792,495,220,66,12,1],...; Number of unilaterally connected digraphs on 3 labeled nodes is 48=6+20+15+6+1.

CROSSREFS

Row sums give A003029. Cf. A057270-A057274, A057276-A057279.

Sequence in context: A105868 A267163 A265163 * A057271 A021480 A201299

Adjacent sequences:  A057272 A057273 A057274 * A057276 A057277 A057278

KEYWORD

nonn,tabf

AUTHOR

Vladeta Jovovic, Goran Kilibarda, Sep 14 2000

STATUS

approved

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Last modified December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)