id:A064382 - OEIS Search Results

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Number of ways to put numbers 1, 2, ..., n*(n+1)/2 in a triangular array of n rows in such a way that each row is increasing or decreasing.

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1, 6, 240, 100800, 605404800, 65703372134400, 155590841484029952000, 9416463528385701835407360000, 16689045681854870055279680279347200000, 976264092939656812770160178186221444104192000000, 2097176933095579995533106263090939623313258344938995712000000 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n) = 2^(n-1) * A022915(n) = 2^(n-1) * (n(n+1)/2)!/(1!2!...n!)`
	CROSSREFS	`A022915.` `Sequence in context: A065948 A052510 A137892 this_sequence A080358 A072228 A056238` `Adjacent sequences: A064379 A064380 A064381 this_sequence A064383 A064384 A064385`
	KEYWORD	`nonn`
	AUTHOR	`Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Sep 27 2001`
	EXTENSIONS	`Corrected and extended by Vladeta Jovovic (vladeta(AT)Eunet.yu), Sep 28 2001`

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Last modified September 4 21:24 EDT 2008. Contains 143414 sequences.

AT&T Labs Research