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%I #6 Dec 07 2016 10:23:51
%S 1,4,24,2880,40320,7257600,479001600,697426329600,20922789888000,
%T 12804747411456000,2432902008176640000,264470759477084160000,
%U 620448401733239439360000,806582922253211271168000000,304888344611713860501504000000,4244045756995056938180935680000000
%N Denominators of coefficients in expansion of 2/(1 + cos(sqrt(x))).
%H Clark Kimberling, <a href="/A279110/b279110.txt">Table of n, a(n) for n = 0..1000</a>
%F 2*A279009.
%e 1/1 + (1/4)x + (1/24)x^2 + (17/2880)x^3 + ... ; 1/1, 1/4, 1/24, 17/2880, 31/40320, ... = |A089171|/A279110.
%t z = 26; t = CoefficientList[Series[2/(1 + Cos[Sqrt[x]]), {x, 0, z}], x];
%t Numerator[t] (* A089171, unsigned *)
%t Denominator[t] (* A279110 *)
%Y Cf. A089171, A279109.
%K nonn,easy,frac
%O 0,2
%A _Clark Kimberling_, Dec 07 2016
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