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Denominators of coefficients in expansion of (2 cos x)/(1 + cos(sqrt(x))).
3

%I #8 Jun 05 2024 18:11:40

%S 1,4,24,2880,40320,7257600,479001600,697426329600,20922789888000,

%T 261321375744000,221172909834240000,4496002911110430720000,

%U 620448401733239439360000,806582922253211271168000000,304888344611713860501504000000,4244045756995056938180935680000000

%N Denominators of coefficients in expansion of (2 cos x)/(1 + cos(sqrt(x))).

%H Clark Kimberling, <a href="/A279240/b279240.txt">Table of n, a(n) for n = 0..1000</a>

%e (1/1) + (1/4)x - (11/24)x^2 - (343/2880)x^3 + (871/40320)x^4 + ... ; 1/1, 1/4, -11/24, -343/2880, ... = A279238/A279240.

%t CoefficientList[Series[2 Cos[x]/(1+Cos[Sqrt[x]]),{x,0,20}],x]//Denominator (* _Harvey P. Dale_, Jun 05 2024 *)

%Y Cf. A279238, A279239.

%K nonn,easy,frac

%O 0,2

%A _Clark Kimberling_, Dec 08 2016

%E Prior Mathematica program corrected by _Harvey P. Dale_, Jun 05 2024