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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A003088 Number of unilateral digraphs with n unlabeled nodes.
(Formerly M2011)
4
1, 1, 2, 11, 171, 8603, 1478644, 870014637 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

REFERENCES

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 218.

R. C. Read (rcread(AT)math.uwaterloo.ca), email to N. J. A. Sloane, 28 August, 2000.

R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..7.

R. W. Robinson, Counting strong digraphs (research announcement), J. Graph Theory 1, 1977, pp. 189-190.

CROSSREFS

Cf. A057270, A003029 (labeled case), A003085, A035512, A051421, A049531, A049512.

Sequence in context: A013050 A051255 A120445 * A121231 A122527 A039747

Adjacent sequences:  A003085 A003086 A003087 * A003089 A003090 A003091

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Note that Read and Wilson incorrectly give a(4) as 172 - thanks to Vladeta Jovovic, Goran Kilibarda for finding this error and for verifying a(5).

a(7) from Sean A. Irvine, Jan 26 2015

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 November 13 01:32 EST 2018. Contains 317118 sequences. (Running on oeis4.)