A165648 - OEIS

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A165648

Number of disconnected simple graphs on n vertices with each component regular.

0, 1, 2, 4, 7, 13, 23, 41, 77, 149, 397, 1246, 21135, 430933, 51156773, 3044120326, 1704554902881 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	FORMULA	`a(n) = A165647(n) - A005177(n)` `= Euler_transformation(A005177)(n) - A005177(n).`
	EXAMPLE	`The a(2)=1 graph is: 2K_1. The a(3)=2 graphs are: 3K_1, K_1+K_2. The a(4)=4 graphs are: 4K_1, 2K_1+K_2, K_1+K_3, 2K_2.`
	CROSSREFS	`Sequence in context: A114832 A136299 A003116 * A078038 A190502 A048888` `Adjacent sequences: A165645 A165646 A165647 * A165649 A165650 A165651`
	KEYWORD	`nonn,hard,more`
	AUTHOR	`Jason Kimberley, Sep 23 2009`

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Last modified February 17 18:34 EST 2012. Contains 206074 sequences.