A013515 - OEIS

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A013515

sech(sec(x)-sech(x))=1-12/4!*x^4+1568/8!*x^8+6840768/12!*x^12...

1, -12, 1568, 6840768, -41485549312, -616649036623872, 51689032519042469888, 309411873154808535072768 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,2`
	MAPLE	`A013515 := proc(n)` `sech(sec(x)-sech(x)) ;` `coeftayl( %, x=0, 4n) ;` `%(4*n)! ;` `end proc: # R. J. Mathar, Dec 16 2011`
	CROSSREFS	`Sequence in context: A015096 A160237 A013474 * A159383 A015011 A034280` `Adjacent sequences: A013512 A013513 A013514 * A013516 A013517 A013518`
	KEYWORD	`sign`
	AUTHOR	`Patrick Demichel (dml(AT)hpfrcu03.france.hp.com)`

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Last modified February 17 08:40 EST 2012. Contains 205998 sequences.