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 A199208 #18 Sep 28 2023 19:19:06
%S A199208 10,37,145,577,2305,9217,36865,147457,589825,2359297,9437185,37748737,
%T A199208 150994945,603979777,2415919105,9663676417,38654705665,154618822657,
%U A199208 618475290625,2473901162497,9895604649985,39582418599937
%N A199208 a(n) = 9*4^n+1.
%H A199208 Vincenzo Librandi, <a href="/A199208/b199208.txt">Table of n, a(n) for n = 0..1000</a>
%H A199208 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4).
%F A199208 a(n) = 4*a(n-1)-3.
%F A199208 a(n) = 5*a(n-1)-4*a(n-2).
%F A199208 G.f.: (10-13*x)/((1-x)*(1-4*x)). - _Bruno Berselli_, Nov 04 2011
%t A199208 NestList[4#-3&,10,30] (* or *) LinearRecurrence[{5,-4},{10,37},30] (* _Harvey P. Dale_, Sep 28 2023 *)
%o A199208 (Magma) [9*4^n+1: n in [0..30]];
%K A199208 nonn,easy
%O A199208 0,1
%A A199208 _Vincenzo Librandi_, Nov 04 2011