A279238 Numerators of coefficients in expansion of (cos x)/(1 + cos(sqrt(x))).

1, 1, -11, -343, 871, 54871, -12359, -102902159, -137687549, 344971369, 20000206271, -34379966953693, -452834430450401, 18163626705916771, 951418549566510481, -381881231033010506527, -4252976361755938012709, -218740547087902859463611

Offset: 0

Author

Clark Kimberling, Dec 08 2016

Keywords

• sign
• easy
• frac

Examples

			(1/2) + (1/8)x - (11/48)x^2 - (343/5760)x^3 + ... ; 1/2, 1/3, -11/48, 1/6480, -343/5760, ... = A279238/A279239.
		

Links

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

Crossrefs

Cf. A279239, A279240.

Programs

Mathematica

z = 26; t = CoefficientList[Series[Cos[x]/(1 + Cos[Sqrt[x]]), {x, 0, z}], x];
Numerator[t]   (* A279238 *)
Denominator[t] (* A279239 *)
%/2 (* A279240 *)