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

%I #4 Dec 12 2016 09:16:55

%S 1,2,24,720,40320,3628800,479001600,87178291200,20922789888000,

%T 6402373705728000,2432902008176640000,1124000727777607680000,

%U 620448401733239439360000,36662860102418694144000000,304888344611713860501504000000,13960676832220582033489920000000

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

%H Clark Kimberling, <a href="/A279309/b279309.txt">Table of n, a(n) for n = 0..1000</a>

%e (2/1) - (1/2)x - (23/24)x^2 + (179/720)x^3 + ... ; 0/1, -1/2, -23/24, 179/720, ... = A279308/A279309.

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

%t Numerator[t] (* A279308 *)

%t Denominator[t] (* A279309 *)

%Y Cf. A279308.

%K nonn,easy,frac

%O 0,2

%A _Clark Kimberling_, Dec 11 2016