login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A121137 Number of labeled directed multigraphs (without loops) with n arcs and no vertex of degree 0. 1
1, 2, 27, 572, 16787, 631362, 28980861, 1570956872, 98212870233, 6956704585554, 550626446263423, 48163137319172436, 4613554511554200251, 480324019903607680066, 54004504167811544647161, 6521368218660772789452944 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
Nathaniel Johnston, Table of n, a(n) for n = 0..50
MAPLE
seq(sum(binomial(m*(m-1)+n-1, n)/2^(m+1), m=0..infinity), n=0..10);
CROSSREFS
Cf. A052170 (unlabeled analog), A104209, A052171.
Sequence in context: A240638 A245050 A242009 * A203429 A153850 A138458
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Sep 06 2006
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)