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%I
%S 1,1,1,7,809,1847,7943,6921461,126235201,1258024561,2288629046003,
%T 80348736972167,111111638337011,40453941942593304589,
%U 258227002122139705201,7316538113501035554721,34747165199239302488636803,2962605017328303351107945687
%N Numerators of coefficients in expansion of 1/(1 + 2 cos(sqrt(x))).
%H Clark Kimberling, <a href="/A279120/b279120.txt">Table of n, a(n) for n = 0..999</a>
%e 1/3 + (1/9)x + (1/36)x^2 + (7/1080)x^3 + ... ; 1/3, 1/9, 1/36, 7/1080, 809/544320, ... = A279120/A279121.
%t z = 30; t = CoefficientList[Series[1/(1 + 2 Cos[Sqrt[x]]), {x, 0, z}], x];
%t Numerator[t]; (* A279120 *)
%t Denominator[t]; (* A279121 *)
%t (1/3) Denominator[t] ; (* A279122 *)
%Y Cf. A279121, A279122.
%K nonn,easy,frac
%O 0,4
%A _Clark Kimberling_, Dec 07 2016
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