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A057277 Triangle T(n,k) of number of digraphs with a source on n unlabeled nodes with k arcs, k=0,1,..,n*(n-1). 2
1, 0, 1, 1, 0, 0, 2, 4, 4, 1, 1, 0, 0, 0, 4, 16, 34, 46, 38, 27, 13, 5, 1, 1, 0, 0, 0, 0, 9, 56, 229, 573, 1058, 1448, 1653, 1487, 1153, 707, 379, 154, 61, 16, 5, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

LINKS

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

EXAMPLE

[1], [0, 1, 1], [0, 0, 2, 4, 4, 1, 1], [0, 0, 0, 4, 16, 34, 46, 38, 27, 13, 5, 1, 1], ....

Number of digraphs with a source on 3 unlabeled nodes is 12=2+4+4+1+1.

CROSSREFS

Row sums give A051421. Cf. A057270-A057276, A057278-A057279.

Sequence in context: A099211 A261761 A094225 * A258712 A238094 A140734

Adjacent sequences:  A057274 A057275 A057276 * A057278 A057279 A057280

KEYWORD

more,nonn,tabf

AUTHOR

Vladeta Jovovic, Goran Kilibard, Sep 14 2000

STATUS

approved

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Last modified February 21 06:25 EST 2018. Contains 299390 sequences. (Running on oeis4.)