A279239 Denominators of coefficients in expansion of (cos x)/(1 + cos(sqrt(x))).

2, 8, 48, 5760, 80640, 14515200, 958003200, 1394852659200, 41845579776000, 522642751488000, 442345819668480000, 8992005822220861440000, 1240896803466478878720000, 1613165844506422542336000000, 609776689223427721003008000000

Offset: 0

Author

Clark Kimberling, Dec 08 2016

Keywords

• nonn
• 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. A279238, 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 *)