A279311 Denominators of coefficients in expansion of (cos x)/(1 - x - x^2).

1, 1, 2, 2, 24, 24, 720, 720, 4480, 40320, 3628800, 3628800, 479001600, 95800320, 2641766400, 87178291200, 1902071808000, 20922789888000, 6402373705728000, 6402373705728000, 810967336058880000, 143111882833920000, 66117689869271040000, 13223537973854208000

Offset

0,3

Links

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

Example

(1/1) + (1/1)x + (3/2)x^2 + (5/2)x^3 + ... ; 1/1, 1/1, 3/2, 5/2, ... = A279310/A279311.

Mathematica

z = 30; t =  CoefficientList[Series[Cos[x]/(1 - x - x^2), {x, 0, z}], x];
Numerator[t]   (* A279310 *)
Denominator[t] (* A279311 *)

Crossrefs

Cf. A279310.

Sequence in context: A120065 A250033 A224479 * A248812 A226243 A226979

Adjacent sequences: A279308 A279309 A279310 * A279312 A279313 A279314

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 11 2016

Status

approved