%I #5 Dec 07 2016 10:22:51
%S 1,3,12,360,181440,1814400,34214400,130767436800,10461394944000,
%T 457312407552000,3649353012264960000,562000363888803840000,
%U 3409057152380436480000,5444434725209176080384000000,152444172305856930250752000000,18946632843727932759736320000000
%N Denominators of coefficients in expansion of 3/(1 + 2 cos(sqrt(x))).
%H Clark Kimberling, <a href="/A279122/b279122.txt">Table of n, a(n) for n = 0..999</a>
%e 1/1 + (1/3)x + (1/12)x^2 + (7/360)x^3 + ... ; 1/1, 1/2, 1/12, 7/360, 809/181440, ... = A279122/A279121.
%t Denominator[CoefficientList[Series[3/(1 + 2 Cos[Sqrt[x]]), {x, 0, 30}], x]]
%Y Cf. A279120, A279122.
%K nonn,easy,frac
%O 0,2
%A _Clark Kimberling_, Dec 07 2016
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