login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A283753 Irregular triangular array read by rows: T(n,k) = the number of non-isomorphic unlabeled weakly connected digraphs on n nodes and with k edges. 3
1, 1, 1, 3, 4, 4, 1, 1, 8, 22, 37, 47, 38, 27, 13, 5, 1, 1, 27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, 154, 61, 16, 5, 1, 1, 91, 582, 2432, 7694, 19646, 42148, 77305, 122953, 170315, 206982, 220768, 207301, 171008, 124110, 78813, 43862, 21209, 8951, 3242, 1043, 288, 76, 17, 5, 1, 1, 350, 3024, 17314, 74676, 266364, 808620, 2144407 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

The range for the subindex k is from n-1 to n(n-1).

Obtained from A054733 by removing leading zeros.

REFERENCES

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

LINKS

Table of n, a(n) for n=1..68.

Marko R. Riedel, Number of distinct connected digraphs

Marko Riedel, Maple code for sequences A052283, A283753.

EXAMPLE

First rows are:

1;

1,    1;

3,    4,   4,   1,    1;

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

27, 108, 326, 667, 1127, 1477, 1665, 1489, 1154, 707, 379, ...

CROSSREFS

Cf. A000273, A000238, A003085, A052283.

Sequence in context: A057279 A054733 A204255 * A120649 A001009 A120650

Adjacent sequences:  A283750 A283751 A283752 * A283754 A283755 A283756

KEYWORD

nonn,tabf

AUTHOR

Marko Riedel, Mar 15 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 23 23:56 EST 2018. Contains 299595 sequences. (Running on oeis4.)