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A012826 cos(sec(x)*arcsinh(x))=1-1/2!*x^2-7/4!*x^4-145/6!*x^6-2063/8!*x^8... 0
1, -1, -7, -145, -2063, -128705, 5154217, -510686033, 254809389793, -27371394484993, 18728499608356185, -5038330344345849489, 3197858289863468529361, -1630641802209014177997505 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..13.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Cos[Sec[x]ArcSinh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Aug 04 2018 *)

CROSSREFS

Sequence in context: A156978 A163028 A296684 * A232363 A102059 A064624

Adjacent sequences:  A012823 A012824 A012825 * A012827 A012828 A012829

KEYWORD

sign

AUTHOR

Patrick Demichel (patrick.demichel(AT)hp.com)

STATUS

approved

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Last modified September 26 08:14 EDT 2021. Contains 347664 sequences. (Running on oeis4.)