A279235 Numerators of coefficients in expansion of 1/(2 - cos(sqrt(x))).

1, -1, 7, -121, 3907, -28963, 15430207, -1619195761, 415698113, -39531606447181, 787393078729637, -329597897026412143, 56485166839707031039, -25018119236152953236111, 17136704858994825564634201, -5470262193930829308041366531, 34416659770990341862308561437707

Offset

0,3

Links

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

Example

(1/1) - (1/2)x + (7/24)x^2 - (121/720)x^3 + ... ; 1/1, -1/2, 7/24, 1/6480, -121/720, ... = A279235/A279236.

Mathematica

z = 26; t =  CoefficientList[Series[1/(2 - Cos[Sqrt[x]]), {x, 0, z}], x];
Numerator[t]   (* A279235 *)
Denominator[t] (* A279236 *)

Crossrefs

Cf. A279236.

Sequence in context: A113267 A274267 A012028 * A094088 A012043 A316730

Adjacent sequences: A279232 A279233 A279234 * A279236 A279237 A279238

Keyword

sign,easy,frac

Author

Clark Kimberling, Dec 08 2016

Status

approved