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A068917 Numerators of coefficients in 1/sin(x) - 1/sinh(x) power series. 9
1, 31, 73, 8191, 5749691557, 3324754717, 22076500342261, 925118910976041358111, 8089941578146657681, 21194489326041221593005331, 3342730069684120811652882591487741, 4204720064739945338027515648494601 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 26 09:03 EDT 2019. Contains 322472 sequences. (Running on oeis4.)