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 A198768 #18 Sep 08 2022 08:46:00
%S A198768 8,44,224,1124,5624,28124,140624,703124,3515624,17578124,87890624,
%T A198768 439453124,2197265624,10986328124,54931640624,274658203124,
%U A198768 1373291015624,6866455078124,34332275390624,171661376953124,858306884765624
%N A198768 a(n) = 9*5^n-1.
%H A198768 Vincenzo Librandi, <a href="/A198768/b198768.txt">Table of n, a(n) for n = 0..1000</a>
%H A198768 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,-5).
%F A198768 a(n) = 5*a(n-1)+4.
%F A198768 a(n) = 6*a(n-1)-5*a(n-2), n > 1.
%F A198768 G.f.: (8 - 4*x)/(1 - 6*x + 5*x^2). - _Vincenzo Librandi_, Jan 03 2013
%t A198768 9 5^Range[0, 20] - 1 (* or *) LinearRecurrence[{6, -5}, {8, 44}, 20] (* _Harvey P. Dale_, Nov 01 2011 *)
%t A198768 CoefficientList[Series[(8 - 4 x)/(1 - 6 x + 5 x^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 03 2013 *)
%o A198768 (Magma) [9*5^n-1: n in [0..30]];
%Y A198768 Cf. A024049, A057651, A081655.
%K A198768 nonn,easy
%O A198768 0,1
%A A198768 _Vincenzo Librandi_, Oct 30 2011