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%I #18 Sep 08 2022 08:45:30
%S 0,9,324,6561,104976,1476225,19131876,234365481,2754990144,
%T 31381059609,348678440100,3797108212689,40669853253264,
%U 429575324987601,4483851321172356,46325504721296025,474373168346071296
%N a(n) = n^2*9^n.
%C Subsequence of A008854 and A047462. [_Bruno Berselli_, Feb 07 2013]
%H Vincenzo Librandi, <a href="/A128788/b128788.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (27,-243,729).
%F G.f.: 9*x*(1+9*x)/(1-9*x)^3. - _Vincenzo Librandi_, Feb 07 2013
%F a(n) = 27*a(n-1) - 243*a(n-2) + 729*a(n-3). - _Vincenzo Librandi_, Feb 07 2013
%t CoefficientList[Series[9 x (1 + 9 x)/(1 - 9 x)^3, {x, 0, 30}], x] (* or *) LinearRecurrence[{27, -243, 729}, {0, 9, 324}, 20] (* _Vincenzo Librandi_, Feb 07 2013 *)
%o (Magma) [n^2*9^n: n in [0..20]]; // _Vincenzo Librandi_, Feb 07 2013
%Y Cf. A007758, A008854, A036289, A047462.
%K nonn,easy
%O 0,2
%A _Mohammad K. Azarian_, Apr 07 2007
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