A012737 - OEIS

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A012737

sech(arctanh(x)*arctan(x))=1-12/4!*x^4-3248/8!*x^8-25240512/12!*x^12...

1, -12, -3248, -25240512, -722745554688, -61363036297915392, -12105663188188359045120, -4791193110632356981925068800 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,2`
	LINKS	`Table of n, a(n) for n=0..7.`
	MATHEMATICA	`With[{nn=34}, Take[CoefficientList[Series[Sech[ArcTanh[x]ArcTan[x]], {x, 0, nn}], x] Range[0, nn-2]!, {1, -1, 4}]] ( Ray Chandler, Nov 28 2016 *)`
	CROSSREFS	`Sequence in context: A268048 A271516 A012603 * A077299 A077749 A077297` `Adjacent sequences: A012734 A012735 A012736 * A012738 A012739 A012740`
	KEYWORD	`sign`
	AUTHOR	`Patrick Demichel (patrick.demichel(AT)hp.com)`
	STATUS	`approved`

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Last modified March 28 08:28 EDT 2023. Contains 361585 sequences. (Running on oeis4.)