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 A083421 #8 Dec 03 2015 09:34:44
%S A083421 1,8,46,242,1234,6218,31186,156122,780994,3905738,19530226,97654202,
%T A083421 488277154,2441398058,12207014866,61035123482,305175715714,
%U A083421 1525878775178,7629394269106,38146972131962,190734862232674
%N A083421 a(n)=2*5^n-2^n.
%C A083421 Third binomial transform of A014551(n+1)
%H A083421 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (7,-10)
%F A083421 G.f.: (1+x)/((1-2x)(1-5x));
%F A083421 e.g.f.: 2exp(5x)-exp(2x).
%F A083421 a(0)=1, a(1)=8, a(n)=7*a(n-1)-10*a(n-2). - _Harvey P. Dale_, Dec 03 2015
%t A083421 Table[2*5^n-2^n,{n,0,20}] (* or *) LinearRecurrence[{7,-10},{1,8},30] (* _Harvey P. Dale_, Dec 03 2015 *)
%K A083421 easy,nonn
%O A083421 0,2
%A A083421 _Paul Barry_, Apr 29 2003