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A165647 Number of simple graphs on n vertices with each component regular. 3
1, 2, 3, 6, 9, 18, 27, 58, 99, 316, 936, 20225, 410571, 50745729, 2993355213, 1701561156737 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..16.

N. J. A. Sloane, Transforms

FORMULA

This sequence is the Euler transformation of A005177.

a(n) = A005177(n) + A165648(n).

EXAMPLE

The a(1)=1 graph is: K_1.

The a(2)=2 graphs are: 2K_1, K_2.

The a(3)=3 graphs are: 3K_1, K_1+K_2, K_3.

The a(4)=6 graphs are: 4K_1, 2K_1+K_2, K_1+K_3, 2K_2, C_4, K_4.

CROSSREFS

Row sums of A275420.

Sequence in context: A018481 A038754 A182522 * A191398 A066313 A224958

Adjacent sequences:  A165644 A165645 A165646 * A165648 A165649 A165650

KEYWORD

nonn,hard,more

AUTHOR

Jason Kimberley, Sep 23 2009

STATUS

approved

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Last modified November 13 10:29 EST 2019. Contains 329093 sequences. (Running on oeis4.)