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 A120990 #9 Jun 22 2013 16:05:58
%S A120990 0,0,12,92,536,2872,14884,75924,384048,1933424,9706556,48650956,
%T A120990 243609160,1219108776,6098732628,30503229188,152544843872,
%U A120990 762810312928,3814309845100,19072324066620,95363944856184,476826697849880
%N A120990 5^n-3^n-2n.
%H A120990 Vincenzo Librandi, <a href="/A120990/b120990.txt">Table of n, a(n) for n = 0..1000</a>
%F A120990 G.f.: 4*x^2*(3-7*x)/((1-x)^2*(1-5*x)*(1-3*x)) . - _Vincenzo Librandi_, Feb 23 2013
%t A120990 CoefficientList[Series[4 x^2 (3 - 7 x)/((1 - x)^2 (1 - 5 x)(1 - 3 x)), {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 23 2013 *)
%Y A120990 Cf. A074606, A005058.
%K A120990 nonn,easy
%O A120990 0,3
%A A120990 _Mohammad K. Azarian_, Aug 19 2006