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%I #27 Jun 13 2015 00:49:12
%S 1,10,90,811,7300,65700,591301,5321710,47895390,431058511,3879526600,
%T 34915739400,314241654601,2828174891410,25453574022690,
%U 229082166204211,2061739495837900,18555655462541100,167000899162869901,1503008092465829110,13527072832192461990
%N Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 1,1,0.
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (9,0,1,-9).
%F G.f.: x*(1+x) / ( (x-1)*(9*x-1)*(1+x+x^2) ). a(n) = A033145(n) + A033145(n-1). - _R. J. Mathar_, Jan 08 2011
%F a(n) = round( (45/364)*9^n ). - _Tani Akinari_, Jul 15 2014
%F a(n+1) = 9*a(n) if n == 2 (mod 3), 9*a(n)+1 otherwise. - _Robert Israel_, Jul 15 2014
%e The first six terms have base 9 representations 1, 11, 110, 1101, 11011, 110110.
%t Module[{nn=30,c},c=PadRight[{},nn,{1,1,0}];Table[FromDigits[Take[c,n],9],{n,nn}]] (* _Harvey P. Dale_, Aug 18 2014 *)
%o (PARI) Vec(x*(1+x) / ( (x-1)*(9*x-1)*(1+x+x^2) ) + O(x^50)) \\ _Michel Marcus_, Jul 15 2014
%Y Cf. A033137 (similar in base 10).
%K nonn,base,easy
%O 1,2
%A _Clark Kimberling_
%E More terms from _Michel Marcus_, Jul 15 2014
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