A069854 Denominators of coefficients of expansion of sinh(x)/sin(x) (even powers only).

1, 3, 18, 1890, 22680, 1247400, 157172400, 6129723600, 81729648000, 127932046704000, 1646485441080480000, 37869165144851040000, 62372742591519360000, 9304453876089900528000000, 5075156659685400288000000, 4459030689216262044805920000000

Offset

0,2

Links

G. C. Greubel, Table of n, a(n) for n = 0..230

Example

G.f. = 1 + (1/3)*x^2 + (1/18)*x^4 + (13/1890)*x^6 + (17/22680)*x^8 + (97/1247400)*x^10 + ...

Maple

a:= n-> denom(coeff(series(sinh(x)/sin(x), x, 2*n+2), x, 2*n)):
seq(a(n), n=0..24);  # Alois P. Heinz, Feb 01 2022

Mathematica

With[{m=60}, CoefficientList[Series[Sinh[x]/Sin[x], {x, 0, m}], x]][[1 ;; ;;  2]]//Denominator (* G. C. Greubel, Jan 31 2022 *)

Prog

(Magma)
m:=60; R<x>:=PowerSeriesRing(Rationals(), m);
b:= Coefficients(R!( Sinh(x)/Sin(x) ));
[Denominator( b[2*n-1] ): n in [1..Floor((m-2)/2)]]; // G. C. Greubel, Jan 31 2022
(Sage) [denominator( ( sinh(x)/sin(x) ).series(x, 2*n+3).list()[2*n] ) for n in (0..60)] # G. C. Greubel, Jan 31 2022

Crossrefs

Cf. A069853.

Sequence in context: A000853 A065402 A131489 * A316369 A291078 A335181

Adjacent sequences: A069851 A069852 A069853 * A069855 A069856 A069857

Keyword

easy,frac,nonn

Author

Benoit Cloitre, May 03 2002

Status

approved