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 A199211 #23 Mar 06 2025 17:42:20
%S A199211 12,45,177,705,2817,11265,45057,180225,720897,2883585,11534337,
%T A199211 46137345,184549377,738197505,2952790017,11811160065,47244640257,
%U A199211 188978561025,755914244097,3023656976385,12094627905537,48378511622145,193514046488577,774056185954305,3096224743817217
%N A199211 a(n) = 11*4^n + 1.
%H A199211 Vincenzo Librandi, <a href="/A199211/b199211.txt">Table of n, a(n) for n = 0..1000</a>
%H A199211 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (5,-4).
%F A199211 a(n) = 4*a(n-1) - 3.
%F A199211 a(n) = 5*a(n-1) - 4*a(n-2).
%F A199211 G.f.: 3*(4-5*x)/((1-x)*(1-4*x)). - _Bruno Berselli_, Nov 04 2011
%F A199211 From _Elmo R. Oliveira_, Mar 06 2025: (Start)
%F A199211 E.g.f.: exp(x)*(1 + 11*exp(3*x)).
%F A199211 a(n) = 3*A199210(n). (End)
%t A199211 11*4^Range[0,30]+1 (* or *) LinearRecurrence[{5,-4},{12,45},30] (* _Harvey P. Dale_, Oct 10 2012 *)
%o A199211 (Magma) [11*4^n+1: n in [0..30]];
%Y A199211 Cf. A199210.
%K A199211 nonn,easy
%O A199211 0,1
%A A199211 _Vincenzo Librandi_, Nov 04 2011