login
A279781
Coefficients in the expansion of 1/([r] + [2r]x + [3r]x^2 + ...); [ ] = floor, r = 9/5.
5
1, -3, 4, -4, 4, -3, -1, 8, -16, 24, -30, 28, -12, -20, 68, -128, 184, -208, 168, -32, -224, 592, -1008, 1344, -1408, 960, 224, -2240, 4928, -7744, 9664, -9216, 4736, 5120, -20608, 39936, -58368, 67840, -57600, 16384, 63488, -180224, 315904, -431104, 463872
OFFSET
0,2
COMMENTS
If n >= 23, then 32 divides a(n).
FORMULA
G.f.: 1/([r] + [2r]x + [3r]x^2 + ...); [ ] = floor, r = 9/5.
G.f.: (1 - x) (1 - x^5)/(1 + 2 x + 2 x^2 + 2 x^3 + 2 x^4).
MATHEMATICA
z = 50; f[x_] := f[x] = Sum[Floor[(9/5)*(k + 1)] x^k, {k, 0, z}]; f[x]
CoefficientList[Series[1/f[x], {x, 0, z}], x]
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Clark Kimberling, Dec 18 2016
STATUS
approved