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 A128991 #22 Sep 08 2022 08:45:30
%S A128991 0,256,9216,196608,3276800,47185920,616562688,7516192768,86973087744,
%T A128991 966367641600,10393820856320,108851651149824,1114904790564864,
%U A128991 11206222510292992,110830772079820800,1080863910568919040
%N A128991 a(n) = (n^3 - n^2)*8^n.
%H A128991 Vincenzo Librandi, <a href="/A128991/b128991.txt">Table of n, a(n) for n = 1..1000</a>
%H A128991 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (32,-384,2048,-4096).
%F A128991 G.f.: 256*x^2*(1+4*x)/(1-8*x)^4. - _Vincenzo Librandi_, Feb 12 2013
%F A128991 a(n) = 32*a(n-1)-384*a(n-2)+2048*a(n-3)-4096*a(n-4). - _Vincenzo Librandi_, Feb 12 2013
%t A128991 CoefficientList[Series[256 x (1 + 4 x)/(1 - 8 x)^4, {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 12 2013 *)
%t A128991 LinearRecurrence[{32,-384,2048,-4096},{0,256,9216,196608},30] (* _Harvey P. Dale_, Aug 25 2013 *)
%o A128991 (Magma) [(n^3-n^2)*8^n: n in [1..25]]; /* or */ I:=[0,256,9216,196608]; [n le 4 select I[n] else 32*Self(n-1)-384*Self(n-2)+2048*Self(n-3)-4096*Self(n-4): n in [1..25]]; // _Vincenzo Librandi_, Feb 12 2013
%Y A128991 Cf. A128796, A036289.
%K A128991 nonn,easy
%O A128991 1,2
%A A128991 _Mohammad K. Azarian_, Apr 30 2007
%E A128991 Offset corrected by _Mohammad K. Azarian_, Nov 20 2008