A054136 a(n) = T(n,2), array T as in A054134.

2, 6, 18, 46, 107, 235, 498, 1032, 2109, 4273, 8612, 17302, 34695, 69495, 139110, 278356, 556865, 1113901, 2227992, 4456194, 8912619, 17825491, 35651258, 71302816, 142605957, 285212265, 570424908, 1140850222, 2281700879

Offset: 2

Author

Clark Kimberling

Keywords

• nonn
• easy

Links

• Index entries for linear recurrences with constant coefficients, signature (5,-9,7,-2).

Crossrefs

Cf. A054134.

Programs

Mathematica

Drop[CoefficientList[Series[x^2(x^4-4x^3+6x^2-4x+2)/((1-2x)(1-x)^3),{x,0,30}],x],2] (* or *) LinearRecurrence[{5,-9,7,-2},{2,6,18,46,107},40] (* Harvey P. Dale, Mar 29 2024 *)

Formula

G.f.: x^2(x^4-4x^3+6x^2-4x+2)/[(1-2x)(1-x)^3].