A068917 Numerators of coefficients in 1/sin(x) - 1/sinh(x) power series.

1, 31, 73, 8191, 5749691557, 3324754717, 22076500342261, 925118910976041358111, 8089941578146657681, 21194489326041221593005331, 3342730069684120811652882591487741, 4204720064739945338027515648494601

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..125

Formula

a(3k+1) = (4k+2)!, a(3k+2) = (4k+4)!, a(3k+3) = (4k+5)!/2.

Example

cosec(x) - cosech(x) = x/3 + 31*x^5/7560 + 73*x^9/1710720 + 8191*x^13/18681062400 + ...

Mathematica

Select[Numerator[CoefficientList[Series[1/Sin[x] - 1/Sinh[x], {x, 0, 500}], x]], # != 0 &] (* G. C. Greubel, Nov 11 2016 *)

Crossrefs

Cf. A068918.

Sequence in context: A155933 A163428 A130468 * A317053 A009408 A165615

Adjacent sequences: A068914 A068915 A068916 * A068918 A068919 A068920

Keyword

easy,frac,nonn

Author

Benoit Cloitre, Mar 29 2002

Status

approved