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A279109 Denominators of coefficients in expansion of 1/(1 + cos(sqrt(x))). 3
2, 8, 48, 5760, 80640, 14515200, 958003200, 1394852659200, 41845579776000, 25609494822912000, 4865804016353280000, 528941518954168320000, 1240896803466478878720000, 1613165844506422542336000000, 609776689223427721003008000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

The numerators are the absolute values of the numbers at A089171.

LINKS

Clark Kimberling, Table of n, a(n) for n = 0..1000

FORMULA

(1/2)*A279110.

EXAMPLE

1/2 + (1/8)x + (1/48)x^2 + (17/5760)x^3 + ... ; 1/2, 1/8, 1/48, 17/5760, 31/80640, ... = |A089171|/A279109.

MATHEMATICA

z = 26; t = CoefficientList[Series[1/(1 + Cos[Sqrt[x]]), {x, 0, z}], x];

u = Numerator[t] (* A089171, unsigned *)

Denominator[t]   (* A279109 *)

CROSSREFS

Cf. A089171, A279110.

Sequence in context: A009745 A009751 A279239 * A183070 A032116 A088181

Adjacent sequences:  A279106 A279107 A279108 * A279110 A279111 A279112

KEYWORD

nonn,easy,frac

AUTHOR

Clark Kimberling, Dec 07 2016

STATUS

approved

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Last modified November 15 22:20 EST 2018. Contains 317252 sequences. (Running on oeis4.)