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 A199412 #12 Sep 08 2022 08:46:00 %S A199412 2,11,65,389,2333,13997,83981,503885,3023309,18139853,108839117, %T A199412 653034701,3918208205,23509249229,141055495373,846332972237, %U A199412 5077997833421,30467987000525,182807922003149,1096847532018893,6581085192113357,39486511152680141 %N A199412 a(n) = (9*6^n+1)/5. %H A199412 Vincenzo Librandi, <a href="/A199412/b199412.txt">Table of n, a(n) for n = 0..1000</a> %H A199412 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (7,-6). %F A199412 a(n) = 6*a(n-1)-1. %F A199412 a(n) = 7*a(n-1)-6*a(n-2). %F A199412 G.f.: (2-3*x)/((1-x)*(1-6*x)). %o A199412 (Magma) [(9*6^n+1)/5: n in [0..30]]; %K A199412 nonn,easy %O A199412 0,1 %A A199412 _Vincenzo Librandi_, Nov 06 2011