A279182 Denominators of coefficients in expansion of 1/(-1 + 2 cos(sqrt(x))).

1, 1, 12, 360, 20160, 1814400, 34214400, 3962649600, 10461394944000, 457312407552000, 1216451004088320000, 562000363888803840000, 309914286580039680000, 10612933187542253568000000, 152444172305856930250752000000, 18946632843727932759736320000000

Offset

0,3

Links

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

Example

1/1 + (1/1)x + (11/12)x^2 + (301/360)x^3 + ... ; 1/1, 1/1, 11/12, 301/360, ... = A279181/A279182.

Mathematica

z = 26; t = CoefficientList[Series[1/(-1 + 2 Cos[Sqrt[x]]), {x, 0, z}], x];
Numerator[t]   (* A279181 *)
Denominator[t] (* A279182 *)

Crossrefs

Cf. A279181.

Sequence in context: A012429 A012631 A327986 * A002674 A012552 A012385

Adjacent sequences: A279179 A279180 A279181 * A279183 A279184 A279185

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 08 2016

Status

approved