A279232 Numerators of coefficients in expansion of 1/(2 + cos(sqrt(x))).

1, 1, 1, 1, -17, -11, -1079, -18197, 522343, 9746101, 81040793, 11644041203, -4125329557, -307899664572491, -2016123696536039, -16774330027463, 2515861894697661407, 1393885832035349216101, 10228935377594654887237, 12758279004615697800956803

Offset

0,5

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. A279233, A279234.

Sequence in context: A040274 A164064 A369490 * A073887 A132955 A217893

Adjacent sequences: A279229 A279230 A279231 * A279233 A279234 A279235

Keyword

sign,easy,frac

Author

Clark Kimberling, Dec 08 2016

Status

approved