A279309 Denominators of coefficients in expansion of (1 + cos(sqrt x))/(cosh x).

1, 2, 24, 720, 40320, 3628800, 479001600, 87178291200, 20922789888000, 6402373705728000, 2432902008176640000, 1124000727777607680000, 620448401733239439360000, 36662860102418694144000000, 304888344611713860501504000000, 13960676832220582033489920000000

Offset

0,2

Links

Clark Kimberling, Table of n, a(n) for n = 0..1000

Example

(2/1) - (1/2)x - (23/24)x^2 + (179/720)x^3 + ... ; 0/1, -1/2, -23/24, 179/720, ... = A279308/A279309.

Mathematica

z = 30; t = CoefficientList[Series[(1 + Cos[Sqrt[x]])/Cosh[x], {x, 0, z}], x];
Numerator[t]   (* A279308 *)
Denominator[t] (* A279309 *)

Crossrefs

Cf. A279308.

Sequence in context: A188959 A093459 A279236 * A010050 A186246 A012161

Adjacent sequences: A279306 A279307 A279308 * A279310 A279311 A279312

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 11 2016

Status

approved