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 A198960 #31 Dec 08 2024 10:19:15
%S A198960 2,26,242,2186,19682,177146,1594322,14348906,129140162,1162261466,
%T A198960 10460353202,94143178826,847288609442,7625597484986,68630377364882,
%U A198960 617673396283946,5559060566555522,50031545098999706,450283905890997362
%N A198960 a(n) = 3*9^n-1.
%H A198960 Vincenzo Librandi, <a href="/A198960/b198960.txt">Table of n, a(n) for n = 0..1000</a>
%H A198960 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (10,-9).
%F A198960 a(n) = 2*A096053(n).
%F A198960 a(n) = 9*a(n-1)+8, n>0.
%F A198960 a(n) = 10*a(n-1)-9*a(n-2), n>1.
%F A198960 G.f.: 2*(1 + 3*x)/(1 - 10*x + 9*x^2). - _Vincenzo Librandi_, Jan 03 2013
%t A198960 CoefficientList[Series[2*(1 + 3*x)/(1 - 10*x + 9*x^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 03 2013 *)
%t A198960 LinearRecurrence[{10,-9},{2,26},30] (* _Harvey P. Dale_, Dec 07 2024 *)
%o A198960 (Magma) [3*9^n-1: n in [0..20]];
%K A198960 nonn,easy
%O A198960 0,1
%A A198960 _Vincenzo Librandi_, Nov 01 2011