Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #24 Sep 26 2017 16:24:43
%S 1,3,9,28,84,252,757,2271,6813,20440,61320,183960,551881,1655643,
%T 4966929,14900788,44702364,134107092,402321277,1206963831,3620891493,
%U 10862674480,32588023440,97764070320,293292210961,879876632883
%N Base 3 digits are, in order, the first n terms of the periodic sequence with initial period 1,0,0.
%H Vincenzo Librandi, <a href="/A033139/b033139.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (3,0,1,-3).
%F G.f.: 1/((1-3*x)*(1-x^3)). - _Paul Barry_, May 02 2003
%F a(n) = 3^(n+3)/26 -1/6 +(5*A049347(n)+7*A049347(n-1))/39. - _R. J. Mathar_, Mar 19 2011
%t CoefficientList[Series[1/((1-3x)(1-x^3)),{x,0,1001}],x] (* _Vincenzo Librandi_, Apr 04 2012 *)
%o (PARI) x='x+O('x^50); Vec(1/((1-3*x)*(1-x^3))) \\ _G. C. Greubel_, Sep 26 2017
%Y Cf. A000975.
%K nonn,base,easy
%O 1,2
%A _Clark Kimberling_