A009123 - OEIS

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A009123

Expansion of cosh(ln(1+sin(x))).

1, 0, 1, -3, 8, -30, 136, -693, 3968, -25260, 176896, -1351383, 11184128, -99680490, 951878656, -9695756073, 104932671488, -1202439837720, 14544442556416, -185185594118763, 2475749026562048, -34674437196568950 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,4`
	COMMENTS	`a(2n) = 1/2*A000182(n+1), a(2n+1) = A012007(n+1) = A009567(2n+1)+1.` `\|a(n)\| = number of even alternating permutations on n letters (offset 1). - Vladeta Jovovic (vladeta(AT)eunet.rs), May 20 2007`
	MATHEMATICA	`Cosh[ Log[ 1+Sin[ x ] ] ]`
	CROSSREFS	`Cf. A000111.` `Sequence in context: A096161 A161779 A074501 * A066764 A059171 A078619` `Adjacent sequences: A009120 A009121 A009122 * A009124 A009125 A009126`
	KEYWORD	`sign,easy`
	AUTHOR	`R. H. Hardin (rhhardin(AT)att.net)`
	EXTENSIONS	`Extended with signs Mar 15 1997 by Olivier Gerard.`

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Last modified February 17 07:30 EST 2012. Contains 205998 sequences.