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A012456 exp((arctan(x))^2)=1+2/2!*x^2-4/4!*x^4+8/6!*x^6+912/8!*x^8... 0
1, 2, -4, 8, 912, -99168, 11815872, -1790856576, 347783278848, -85244795874816, 25888104843574272, -9570587679263078400, 4239434238319441121280, -2218976274384029204766720 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

MATHEMATICA

With[{nn=30}, Take[CoefficientList[Series[Exp[ArcTan[x]^2], {x, 0, nn}], x] Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Apr 24 2016 *)

CROSSREFS

Sequence in context: A061089 A067499 A135212 * A071686 A296742 A103097

Adjacent sequences:  A012453 A012454 A012455 * A012457 A012458 A012459

KEYWORD

sign

AUTHOR

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

EXTENSIONS

Definition clarified by Harvey P. Dale, Apr 24 2016

STATUS

approved

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Last modified May 26 20:51 EDT 2022. Contains 354092 sequences. (Running on oeis4.)