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A012238 cosh(arctan(arctanh(x)))=1+1/2!*x^2+1/4!*x^4+49/6!*x^6+1345/8!*x^8... 0
1, 1, 1, 49, 1345, 105441, 10336833, 1580651409, 316289380737, 83559601907649, 27709107620492673, 11345006679686949105, 5605389007592066373825, 3292126822668986935347105, 2265914784466771293436282305, 1806802766658673683522189272145 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..15.

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Cosh[ArcTan[ArcTanh[x]]], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Mar 02 2015 *)

CROSSREFS

Sequence in context: A115999 A228258 A282930 * A036226 A032655 A001458

Adjacent sequences:  A012235 A012236 A012237 * A012239 A012240 A012241

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

More terms from Harvey P. Dale, Mar 02 2015

STATUS

approved

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Last modified October 22 12:30 EDT 2019. Contains 328318 sequences. (Running on oeis4.)