login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A091478 Table of graphs with n (>=1) nodes and k (>=0) edges. Each type of object labeled from its own label set. 2
1, 1, 1, 1, 3, 6, 6, 1, 6, 30, 120, 360, 720, 720, 1, 10, 90, 720, 5040, 30240, 151200, 604800, 1814400, 3628800, 3628800, 1, 15, 210, 2730, 32760, 360360, 3603600, 32432400, 259459200, 1816214400, 10897286400, 54486432000, 217945728000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

REFERENCES

F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, p. 114 (2.4.44).

LINKS

Table of n, a(n) for n=1..38.

FORMULA

a(n, k) = k!*binomial(binomial(n, 2), k).

EXAMPLE

1; 1,1; 1,3,6,6; 1,6,30,120,360,720,720; row lengths in A000124(n+1).

CROSSREFS

Row sums: A091479. Columns 0-2: A000012, A000217(n-1), A033487(n-2).

a(n, A000217(n-1)) = A052295(n-1). Cf. A006125, A008406.

Sequence in context: A285628 A319886 A021736 * A239567 A198239 A086727

Adjacent sequences:  A091475 A091476 A091477 * A091479 A091480 A091481

KEYWORD

nonn,tabf

AUTHOR

Christian G. Bower, Jan 13 2004

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 10:49 EDT 2020. Contains 334681 sequences. (Running on oeis4.)