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 A199318 #12 Sep 08 2022 08:46:00
%S A199318 4,19,109,649,3889,23329,139969,839809,5038849,30233089,181398529,
%T A199318 1088391169,6530347009,39182082049,235092492289,1410554953729,
%U A199318 8463329722369,50779978334209,304679870005249,1828079220031489,10968475320188929
%N A199318 3*6^n+1.
%H A199318 Vincenzo Librandi, <a href="/A199318/b199318.txt">Table of n, a(n) for n = 0..1000</a>
%H A199318 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (7,-6).
%F A199318 a(n) = 6*a(n-1)-5.
%F A199318 a(n) = 7*a(n-1)-6*a(n-2).
%F A199318 G.f.: (4-9*x)/((1-x)*(1-6*x)).
%t A199318 3 6^Range[0,20] +1 (* or *) LinearRecurrence[{7,-6},{4,19},30] (* _Harvey P. Dale_, Sep 30 2020 *)
%o A199318 (Magma) [3*6^n+1: n in [0..30]];
%K A199318 nonn,easy
%O A199318 0,1
%A A199318 _Vincenzo Librandi_, Nov 05 2011