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A012845 cos(sec(x)*arctanh(x))=1-1/2!*x^2-19/4!*x^4-565/6!*x^6-24743/8!*x^8... 0
1, -1, -19, -565, -24743, -1450985, -100090043, -5608180253, 703874231473, 601015521145391, 309193460848468125, 160230604230030181371, 91310347371287711776777, 58721857461984188996135495 (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]ArcTanh[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Oct 25 2011 *)

CROSSREFS

Sequence in context: A035278 A092611 A008990 * A284111 A142023 A075879

Adjacent sequences:  A012842 A012843 A012844 * A012846 A012847 A012848

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified October 15 17:45 EDT 2021. Contains 348033 sequences. (Running on oeis4.)