A279235 - OEIS

%I #7 Dec 10 2016 22:39:23

%S 1,-1,7,-121,3907,-28963,15430207,-1619195761,415698113,

%T -39531606447181,787393078729637,-329597897026412143,

%U 56485166839707031039,-25018119236152953236111,17136704858994825564634201,-5470262193930829308041366531,34416659770990341862308561437707

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

%H Clark Kimberling, <a href="/A279235/b279235.txt">Table of n, a(n) for n = 0..1000</a>

%e (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.

%t z = 26; t =  CoefficientList[Series[1/(2 - Cos[Sqrt[x]]), {x, 0, z}], x];

%t Numerator[t]   (* A279235 *)

%t Denominator[t] (* A279236 *)

%Y Cf. A279236.

%K sign,easy,frac

%O 0,3

%A _Clark Kimberling_, Dec 08 2016