A009805 - OEIS

A009805

Expansion of sin(tan(x)*sin(x))/2.

1, -124, 262096, -2681078464, 83993259325696, -6291889632188161024, 963296773204704677810176, -270352239123704851078462357504, 128399592149905444543967414059073536

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..8.

MATHEMATICA

Tanh[ Sinh[ x ]*Sin[ x ] ]/2 (* [ x^(4n+2) ] *)

With[{nn=34}, Take[CoefficientList[Series[Tanh[Sinh[x]Sin[x]]/2, {x, 0, nn}], x] Range[0, nn]!, {3, -1, 4}]] (* Harvey P. Dale, May 28 2019 *)

CROSSREFS

Cf. A023702.

Sequence in context: A146516 A146546 A146553 * A227393 A005080 A174733

Adjacent sequences: A009802 A009803 A009804 * A009806 A009807 A009808

KEYWORD

sign

AUTHOR

R. H. Hardin

EXTENSIONS

Extended with signs by Olivier Gérard, Mar 15 1997

STATUS

approved