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A012044 sec(sin(arcsinh(x)))=1+1/2!*x^2-3/4!*x^4+21/6!*x^6-647/8!*x^8... 0
1, 1, -3, 21, -647, 45161, -4655115, 671831421, -131445679375, 33601481453521, -10874248371483155, 4345212201159011301, -2101132542287329737623, 1209250716473417141359161 (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[Sec[Sin[ArcSinh[x]]], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Nov 28 2011 *)

CROSSREFS

Sequence in context: A180999 A181003 A093549 * A098918 A001699 A291967

Adjacent sequences:  A012041 A012042 A012043 * A012045 A012046 A012047

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified February 18 02:20 EST 2018. Contains 299297 sequences. (Running on oeis4.)