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A012041 tanh(sin(arcsinh(x)))=x-4/3!*x^3+76/5!*x^5-3312/7!*x^7+255952/9!*x^9... 1
1, -4, 76, -3312, 255952, -30728512, 5281229760, -1228900532992, 371761489090816, -141763213277045760, 66504626862819552256, -37635004127910391803904, 25277676503178610861756416 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..220

FORMULA

a(n) ~ c * (-1)^n * (2*n)! * n / r^(2*n), where r = sin(arcsinh(Pi/2)) = 0.9436207924237..., c = 0.79859796313... . - Vaclav Kotesovec, Feb 04 2015

MATHEMATICA

nn = 20; Table[(CoefficientList[Series[Tanh[Sin[ArcSinh[x]]], {x, 0, 2*nn+1}], x] * Range[0, 2*nn+1]!)[[n]], {n, 2, 2*nn, 2}] (* Vaclav Kotesovec, Feb 03 2015 *)

CROSSREFS

Sequence in context: A187542 A009631 A012020 * A024258 A012101 A012080

Adjacent sequences:  A012038 A012039 A012040 * A012042 A012043 A012044

KEYWORD

sign

AUTHOR

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

STATUS

approved

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Last modified January 25 16:01 EST 2022. Contains 350572 sequences. (Running on oeis4.)