A027114 a(n) = A027113(n, n+2).

3, 9, 20, 40, 77, 145, 270, 500, 923, 1701, 3132, 5764, 10605, 19509, 35886, 66008, 121411, 223313, 410740, 755472, 1389533, 2555753, 4700766, 8646060, 15902587, 29249421, 53798076, 98950092, 181997597, 334745773, 615693470

Offset: 2

Author

Clark Kimberling

Keywords

• nonn

Links

• Index entries for linear recurrences with constant coefficients, signature (2,0,0,-1).

Crossrefs

Equals A089068(n+2) - 3.

Programs

Mathematica

CoefficientList[Series[(3+3x+2x^2)/((1-x)(1-x-x^2-x^3)),{x,0,40}],x] (* or *) LinearRecurrence[{2,0,0,-1},{3,9,20,40},40] (* Harvey P. Dale, Sep 26 2017 *)

Formula

G.f.: [3+3x+2x^2]/[(1-x)(1-x-x^2-x^3)].