A213933 G.f.: (1+x+x^2+2*x^5-2*x^10)/(1-3*x^3).

1, 1, 1, 3, 3, 5, 9, 9, 15, 27, 25, 45, 81, 75, 135, 243, 225, 405, 729, 675, 1215, 2187, 2025, 3645, 6561, 6075, 10935, 19683, 18225, 32805, 59049, 54675, 98415, 177147, 164025, 295245, 531441, 492075, 885735, 1594323, 1476225, 2657205, 4782969, 4428675, 7971615

Offset

0,4

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..1000 [a(0)=1 inserted by Georg Fischer, Jan 17 2021]

Index entries for linear recurrences with constant coefficients, signature (0,0,3).

Mathematica

lst = {}; Do[a = Ceiling[25*3^(n - 3)]; b = Floor[5*3^(n - 1)]; c = 3^(n + 1); AppendTo[lst, {a, b, c}], {n, 0, 14}]; Prepend[Flatten@lst, 1]
CoefficientList[Series[(1 + x + x^2 + 2*x^5 - 2*x^10)/(1 - 3*x^3), {x, 0, 44}], x] (* Vincenzo Librandi, Jul 12 2012 *)
LinearRecurrence[{0, 0, 3}, {1, 1, 1, 3, 3, 5, 9, 9, 15, 27, 25}, 51] (* Harvey P. Dale, Jan 12 2020 *)

Prog

(PARI) my(x='x+O('x^50)); Vec((1+x+x^2+2*x^5-2*x^10)/(1-3*x^3)) \\ Michel Marcus, Jan 16 2021

Crossrefs

Cf. A000792, A091916.

Sequence in context: A287195 A179437 A136791 * A091916 A102437 A319794

Adjacent sequences: A213930 A213931 A213932 * A213934 A213935 A213936

Keyword

nonn,easy

Author

Arkadiusz Wesolowski, Jun 25 2012

Extensions

Replaced unclear definition with a precise generating function from Bruno Berselli, Jun 27 2012. - N. J. A. Sloane, Jan 11 2021

Name changed and initial term added by Arkadiusz Wesolowski, Dec 20 2020

Status

approved