A279780 Coefficients in the expansion of 1/([r] + [2r]x + [3r]x^2 + ...); [ ] = floor, r = 8/5.

1, -3, 5, -9, 17, -30, 52, -90, 154, -262, 446, -758, 1286, -2182, 3702, -6278, 10646, -18054, 30614, -51910, 88022, -149254, 253078, -429126, 727638, -1233798, 2092054, -3547334, 6014934, -10199046, 17293718, -29323590, 49721686, -84309126, 142956310

Offset: 0

Author

Clark Kimberling, Dec 18 2016

Keywords

• sign
• easy

Comments

If n > 4, then a(n) is even.

Links

• Clark Kimberling, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (-2,-1,-2,-2).

Crossrefs

Cf. A279634, A279778, A279779, A279781, A289260.

Programs

Mathematica

z = 50; f[x_] := f[x] = Sum[Floor[(8/5)*(k + 1)] x^k, {k, 0, z}]; f[x]
CoefficientList[Series[1/f[x], {x, 0, z}], x]

Formula

G.f.: 1/([r] + [2r]x + [3r]x^2 + ...); [ ] = floor, r = 8/5.

G.f.: (1 - x) (1 - x^5)/(1 + 2 x + x^2 + 2 x^3 + 2 x^4).