A279233 Denominators of coefficients in expansion of 1/(2 + cos(sqrt(x))).

3, 18, 216, 6480, 1088640, 3628800, 4311014400, 2353813862400, 564915326976000, 57621363351552000, 5971668565524480000, 30348019649995407360000, 75801388447047352320000, 32666608351255056482304000000, 2743995101505424744513536000000

Offset

0,1

Links

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

Example

(1/3) + (1/18)x + (1/216)x^2 + (1/6480)x^3 - (17/1088640)x^4 + ... ; 1/3, 1/18, 1/216, 1/6480, -17/1088640, ... = A279232/A279233.

Mathematica

z = 26; t = CoefficientList[Series[1/(2 + Cos[Sqrt[x]]), {x, 0, z}], x];
Numerator[t]   (* A279232 *)
Denominator[t] (* A279233 *)
%/3  (* A279234 *)

Crossrefs

Cf. A279232, A279234.

Sequence in context: A319580 A132727 A111841 * A071605 A340336 A222686

Adjacent sequences: A279230 A279231 A279232 * A279234 A279235 A279236

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 08 2016

Status

approved