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Denominators of coefficients in expansion of (cos(sqrt x))/(1 - x - x^2).
2

%I #6 Dec 15 2016 03:02:27

%S 1,2,24,720,8064,3628800,479001600,87178291200,20922789888000,

%T 98498057011200,187146308321280000,66117689869271040000,

%U 36496964807837614080000,403291461126605635584000000,60977668922342772100300800000,13960676832220582033489920000000

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

%H Clark Kimberling, <a href="/A279331/b279331.txt">Table of n, a(n) for n = 0..1000</a>

%e (1/1) + (1/2)*x + (37/24)*x^2 + (1469/720)*x^3 + ... , therefore: 1/1, 1/2, 37/24, 1469/720, ... = A279330/A279331.

%t z = 30; t = CoefficientList[Series[Cos[Sqrt[x]]/(1 - x - x^2), {x, 0, z}], x];

%t Numerator[t] (* A279330 *)

%t Denominator[t] (* A279331 *)

%Y Cf. A279330.

%K nonn,frac,easy

%O 0,2

%A _Clark Kimberling_, Dec 12 2016