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A012633 sech(arcsinh(x)*arctan(x))=1-12/4!*x^4+360/6!*x^6-9968/8!*x^8... 0
1, 0, -12, 360, -9968, -20160, 62513088, -11126763648, 1288066390272, 19652873951232, -83472832434404352, 36956701107235768320, -9713959158890293555200, -340935340396162516992000 (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[Sech[ArcSinh[x]ArcTan[x]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jul 21 2018 *)

CROSSREFS

Sequence in context: A012431 A012386 A130213 * A009079 A012379 A012424

Adjacent sequences:  A012630 A012631 A012632 * A012634 A012635 A012636

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified May 21 00:36 EDT 2022. Contains 353886 sequences. (Running on oeis4.)