A230382 - OEIS

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A230382

Number of ascending runs of length n in the permutations of [2n].

1, 2, 21, 312, 5880, 133920, 3575880, 109549440, 3788104320, 145957593600, 6201593798400, 288084016281600, 14525808782284800, 790129980896256000, 46120599397192320000, 2875600728738017280000, 190740227037467627520000, 13411608375592258191360000 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,2`
	LINKS	`Alois P. Heinz, Table of n, a(n) for n = 0..300`
	FORMULA	`For n>0, a(n) = (n^2+n+1)(2n)!/((n+2)*n!). - Vaclav Kotesovec, Oct 18 2013`
	MAPLE	a:= proc(n) option remember; `if`(n<2, 1+n, `2(2n-1)(n+1)(n^2+n+1)a(n-1)/((n+2)(n^2-n+1)))` `end:` `seq(a(n), n=0..25);`
	CROSSREFS	`A diagonal of A122843.` `Sequence in context: A097627 A094797 A234525 * A196629 A196637 A240997` `Adjacent sequences: A230379 A230380 A230381 * A230383 A230384 A230385`
	KEYWORD	`nonn`
	AUTHOR	`Alois P. Heinz, Oct 17 2013`
	STATUS	`approved`

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Last modified August 17 17:25 EDT 2017. Contains 290648 sequences.