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A054733 Triangle of number of (weakly) connected unlabeled digraphs with n nodes and k arcs (n >=2, k >= 1). 2
1, 1, 0, 3, 4, 4, 1, 1, 0, 0, 8, 22, 37, 47, 38, 27, 13, 5, 1, 1, 0, 0, 0, 27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, 154, 61, 16, 5, 1, 1, 0, 0, 0, 0, 91, 582, 2432, 7694, 19646, 42148, 77305, 122953, 170315, 206982, 220768, 207301, 171008 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973.

LINKS

Table of n, a(n) for n=2..58.

R. J. Mathar,Statistics on Small Graphs, arXiv:1709.09000  (2017) Table 75.

EXAMPLE

1,1;

0,3,4,4,1,1;

0,0,8,22,37,47,38,27,13,5,1,1;

the last batch giving the numbers of connected digraphs with 4 nodes and from 1 to 12 arcs.

CROSSREFS

Cf. A003085 (row sums), A053454 (column sums), A062735 (labeled).

Cf. A283753.

Sequence in context: A132723 A260180 A057279 * A204255 A283753 A120649

Adjacent sequences:  A054730 A054731 A054732 * A054734 A054735 A054736

KEYWORD

easy,nonn,tabf

AUTHOR

Vladeta Jovovic, Apr 21 2000

STATUS

approved

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Last modified September 15 04:09 EDT 2019. Contains 327062 sequences. (Running on oeis4.)