A152684 - OEIS

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A152684

a(n) is the number of top-down sequences (F_1,F_2, ..., F_n) whereas each F_i is a labeled forest on n nodes, containing i directed rooted trees. F_(i+1) is proper subset of F_i.

1, 2, 18, 384, 15000, 933120, 84707280, 10569646080, 1735643790720, 362880000000000, 94121726392108800, 29658516531078758400 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	FORMULA	`a(n)=n^(n-2)*(n!)`
	EXAMPLE	`a(1)=1^(1-2)(1!)=1` `a(2)=2^(2-2)(2!)=2` `a(3)=3^(3-2)*(3!)=18`
	CROSSREFS	`Sequence in context: A123311 A181536 A132911 * A201732 A141074 A082402` `Adjacent sequences: A152681 A152682 A152683 * A152685 A152686 A152687`
	KEYWORD	`nonn`
	AUTHOR	`Fabian Nedic (fabian.nedic(AT)gmx.de), Dec 10 2008`

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Last modified February 15 21:56 EST 2012. Contains 205860 sequences.