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 A024103 #15 Sep 08 2022 08:44:48
%S A024103 1,8,77,720,6545,59024,531405,4782920,43046657,387420408,3486784301,
%T A024103 31381059488,282429536337,2541865828160,22876792454765,
%U A024103 205891132094424,1853020188851585,16677181699666280,150094635296998797
%N A024103 a(n) = 9^n - n^2.
%H A024103 Vincenzo Librandi, <a href="/A024103/b024103.txt">Table of n, a(n) for n = 0..400</a>
%H A024103 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (12,-30,28,-9).
%F A024103 G.f.: (1-4*x+11*x^2+8*x^3)/((1-9*x)*(1-x)^3). - _Vincenzo Librandi_, Oct 06 2014
%F A024103 a(n) = 12*a(n-1) -30*a(n-2) +28*a(n-3) -9*a(n-4) for n>3. - _Vincenzo Librandi_, Oct 06 2014
%F A024103 a(n) = A001019(n) - A000290(n). - _Michel Marcus_, Oct 06 2014
%t A024103 Table[9^n - n^2, {n, 0, 25}] (* or *) CoefficientList[Series[(1 - 4 x + 11 x^2 + 8 x^3)/((1 - 9 x) (1 - x)^3), {x, 0, 30}], x] (* _Vincenzo Librandi_, Oct 06 2014 *)
%o A024103 (Magma) [9^n-n^2: n in [0..25]]; // _Vincenzo Librandi_, Jul 06 2011
%Y A024103 Cf. A000290, A001019.
%Y A024103 Cf. similar sequences listed in A024025.
%K A024103 nonn,easy
%O A024103 0,2
%A A024103 _N. J. A. Sloane_