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A279110 Denominators of coefficients in expansion of 2/(1 + cos(sqrt(x))). 2
1, 4, 24, 2880, 40320, 7257600, 479001600, 697426329600, 20922789888000, 12804747411456000, 2432902008176640000, 264470759477084160000, 620448401733239439360000, 806582922253211271168000000, 304888344611713860501504000000, 4244045756995056938180935680000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

FORMULA

2*A279009.

EXAMPLE

1/1 + (1/4)x + (1/24)x^2 + (17/2880)x^3 + ... ; 1/1, 1/4, 1/24, 17/2880, 31/40320, ... = |A089171|/A279110.

MATHEMATICA

z = 26; t = CoefficientList[Series[2/(1 + Cos[Sqrt[x]]), {x, 0, z}], x];

Numerator[t]   (* A089171, unsigned *)

Denominator[t] (* A279110 *)

CROSSREFS

Cf.  A089171, A279109.

Sequence in context: A110972 A065711 A279240 * A077093 A077092 A092435

Adjacent sequences:  A279107 A279108 A279109 * A279111 A279112 A279113

KEYWORD

nonn,easy,frac

AUTHOR

Clark Kimberling, Dec 07 2016

STATUS

approved

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Last modified March 25 22:28 EDT 2019. Contains 321477 sequences. (Running on oeis4.)