This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A128788 #18 Sep 08 2022 08:45:30
%S A128788 0,9,324,6561,104976,1476225,19131876,234365481,2754990144,
%T A128788 31381059609,348678440100,3797108212689,40669853253264,
%U A128788 429575324987601,4483851321172356,46325504721296025,474373168346071296
%N A128788 a(n) = n^2*9^n.
%C A128788 Subsequence of A008854 and A047462. [_Bruno Berselli_, Feb 07 2013]
%H A128788 Vincenzo Librandi, <a href="/A128788/b128788.txt">Table of n, a(n) for n = 0..1000</a>
%H A128788 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (27,-243,729).
%F A128788 G.f.: 9*x*(1+9*x)/(1-9*x)^3. - _Vincenzo Librandi_, Feb 07 2013
%F A128788 a(n) = 27*a(n-1) - 243*a(n-2) + 729*a(n-3). - _Vincenzo Librandi_, Feb 07 2013
%t A128788 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 A128788 (Magma) [n^2*9^n: n in [0..20]]; // _Vincenzo Librandi_, Feb 07 2013
%Y A128788 Cf. A007758, A008854, A036289, A047462.
%K A128788 nonn,easy
%O A128788 0,2
%A A128788 _Mohammad K. Azarian_, Apr 07 2007