A012348 - OEIS

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A012348

arctanh(arcsin(x)*arcsin(x))=2/2!*x^2+8/4!*x^4+368/6!*x^6+18048/8!*x^8...

0, 2, 8, 368, 18048, 2068992, 306585600, 69776517120, 20465184768000, 7935055273328640, 3823692307188940800, 2274500815301011046400, 1624840840672099644211200, 1378125905023775157056962560

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

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

FORMULA

a(n) ~ (2*n-1)! / (sin(1))^(2*n). - Vaclav Kotesovec, Feb 05 2015

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[ArcTanh[ArcSin[x]^2], {x, 0, 2*nn}], x] * Range[0, 2*nn]!)[[n]], {n, 1, 2*nn+1, 2}] (* Vaclav Kotesovec, Feb 05 2015 *)

CROSSREFS

Sequence in context: A102597 A009836 A012342 * A219994 A014185 A367998

Adjacent sequences: A012345 A012346 A012347 * A012349 A012350 A012351

KEYWORD

nonn

AUTHOR

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

EXTENSIONS

Prepended missing a(0)=0 from Vaclav Kotesovec, Feb 05 2015

STATUS

approved