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 A198765 #18 Sep 08 2022 08:46:00
%S A198765 6,34,174,874,4374,21874,109374,546874,2734374,13671874,68359374,
%T A198765 341796874,1708984374,8544921874,42724609374,213623046874,
%U A198765 1068115234374,5340576171874,26702880859374,133514404296874
%N A198765 7*5^n-1.
%H A198765 Vincenzo Librandi, <a href="/A198765/b198765.txt">Table of n, a(n) for n = 0..1000</a>
%H A198765 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (6,-5).
%F A198765 a(n) = 5*a(n-1) + 4.
%F A198765 a(n) = 6*a(n-1) - 5*a(n-2), n > 1.
%F A198765 G.f.: 2*(3 - x)/(1 - 6*x + 5*x^2). - _Vincenzo Librandi_, Jan 04 2013
%t A198765 CoefficientList[Series[2*(3 - x)/(1 - 6*x + 5*x^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 04 2013 *)
%t A198765 7 * 5^Range[0, 19] - 1 (* _Alonso del Arte_, Dec 05 2013 *)
%o A198765 (Magma) [7*5^n-1: n in [0..30]];
%Y A198765 Cf. A024049, A057651, A081655.
%K A198765 nonn,easy
%O A198765 0,1
%A A198765 _Vincenzo Librandi_, Oct 30 2011