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A279120 Numerators of coefficients in expansion of 1/(1 + 2 cos(sqrt(x))). 3

%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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Last modified October 23 08:57 EDT 2019. Contains 328345 sequences. (Running on oeis4.)