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A279121
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Denominators of coefficients in expansion of 1/(1 + 2 cos(sqrt(x))).
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3
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3, 9, 36, 1080, 544320, 5443200, 102643200, 392302310400, 31384184832000, 1371937222656000, 10948059036794880000, 1686001091666411520000, 10227171457141309440000, 16333304175627528241152000000, 457332516917570790752256000000, 56839898531183798279208960000000
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OFFSET
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0,1
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LINKS
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Clark Kimberling, Table of n, a(n) for n = 0..999
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EXAMPLE
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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.
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MATHEMATICA
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z = 30; t = CoefficientList[Series[1/(1 + 2 Cos[Sqrt[x]]), {x, 0, z}], x];
Numerator[t]; (* A279120 *)
Denominator[t]; (* A279121 *)
(1/3) Denominator[t] ; (* A279122 *)
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CROSSREFS
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Cf. A279120, A279122.
Sequence in context: A163144 A128094 A135474 * A076964 A034808 A018398
Adjacent sequences: A279118 A279119 A279120 * A279122 A279123 A279124
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KEYWORD
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nonn,easy,frac
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AUTHOR
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Clark Kimberling, Dec 07 2016
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STATUS
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approved
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