A279181 Numerators of coefficients in expansion of 1/(-1 + 2 cos(sqrt(x))).

1, 1, 11, 301, 15371, 1261501, 21692333, 2291003591, 5515342166891, 219856146354043, 533289474412481051, 224671379367784281901, 112978424972711121811, 3528028730755504686511279, 46211522130188693681603906171, 5237381988676259999443664085643

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. A279182.

Sequence in context: A101269 A012184 A012027 * A002114 A012192 A012079

Adjacent sequences: A279178 A279179 A279180 * A279182 A279183 A279184

Keyword

nonn,easy,frac

Author

Clark Kimberling, Dec 08 2016

Status

approved