A128103 - OEIS

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A128103

Number of permutations with an even number of rises.

1, 1, 2, 12, 68, 360, 2384, 20160, 185408, 1814400, 19781504, 239500800, 3124694528, 43589145600, 652885305344, 10461394944000, 177948646719488, 3201186852864000, 60808005761859584, 1216451004088320000 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,3`
	LINKS	`F. C. S. Brown, T. M. A. Fink and K. Willbrand, On arithmetic and asymptotic properties of up-down numbers`
	FORMULA	`E.g.f.: 1/2 [z/(1-z) + tanh(z) ].`
	CROSSREFS	`Sequence in context: A000954 A056636 A174327 * A078839 A026306 A116398` `Adjacent sequences: A128100 A128101 A128102 * A128104 A128105 A128106`
	KEYWORD	`nonn`
	AUTHOR	`Ralf Stephan, May 09 2007`

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Last modified February 16 23:45 EST 2012. Contains 205978 sequences.