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 A279121 Denominators of coefficients in expansion of 1/(1 + 2 cos(sqrt(x))). 3
 3, 9, 36, 1080, 544320, 5443200, 102643200, 392302310400, 31384184832000, 1371937222656000, 10948059036794880000, 1686001091666411520000, 10227171457141309440000, 16333304175627528241152000000, 457332516917570790752256000000, 56839898531183798279208960000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Clark Kimberling, Table of n, a(n) for n = 0..999 EXAMPLE 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. MATHEMATICA 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 *) CROSSREFS Cf. A279120, A279122. Sequence in context: A163144 A128094 A135474 * A076964 A034808 A018398 Adjacent sequences: A279118 A279119 A279120 * A279122 A279123 A279124 KEYWORD nonn,easy,frac AUTHOR Clark Kimberling, Dec 07 2016 STATUS approved

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Last modified August 2 22:39 EDT 2024. Contains 374875 sequences. (Running on oeis4.)