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%I #67 Jan 17 2021 06:24:56
%S 1,1,1,3,3,5,9,9,15,27,25,45,81,75,135,243,225,405,729,675,1215,2187,
%T 2025,3645,6561,6075,10935,19683,18225,32805,59049,54675,98415,177147,
%U 164025,295245,531441,492075,885735,1594323,1476225,2657205,4782969,4428675,7971615
%N G.f.: (1+x+x^2+2*x^5-2*x^10)/(1-3*x^3).
%H Vincenzo Librandi, <a href="/A213933/b213933.txt">Table of n, a(n) for n = 0..1000</a> [a(0)=1 inserted by _Georg Fischer_, Jan 17 2021]
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,3).
%t 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]
%t 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 *)
%t LinearRecurrence[{0,0,3},{1,1,1,3,3,5,9,9,15,27,25},51] (* _Harvey P. Dale_, Jan 12 2020 *)
%o (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
%Y Cf. A000792, A091916.
%K nonn,easy
%O 0,4
%A _Arkadiusz Wesolowski_, Jun 25 2012
%E Replaced unclear definition with a precise generating function from _Bruno Berselli_, Jun 27 2012. - _N. J. A. Sloane_, Jan 11 2021
%E Name changed and initial term added by _Arkadiusz Wesolowski_, Dec 20 2020