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 A198687 #19 Jul 23 2024 15:14:48
%S A198687 4,34,244,1714,12004,84034,588244,4117714,28824004,201768034,
%T A198687 1412376244,9886633714,69206436004,484445052034,3391115364244,
%U A198687 23737807549714,166164652848004,1163152569936034,8142067989552244,56994475926865714
%N A198687 5*7^n-1.
%H A198687 Vincenzo Librandi, <a href="/A198687/b198687.txt">Table of n, a(n) for n = 0..1000</a>
%H A198687 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-7).
%F A198687 a(n) = 7*a(n-1)+6 = 8*a(n-1)-7*a(n-2), n>1.
%F A198687 G.f.:(4+2*x)/((1-x)*(1-7*x)). - _Vincenzo Librandi_, Jul 06 2012
%t A198687 CoefficientList[Series[(4+2*x)/((1-x)*(1-7*x)),{x,0,40}],x] (* _Vincenzo Librandi_, Jul 06 2012 *)
%t A198687 LinearRecurrence[{8,-7},{4,34},20] (* _Harvey P. Dale_, Jul 23 2024 *)
%o A198687 (Magma) [5*7^n-1: n in [0..30]]
%Y A198687 Cf. A048473, A081655, A198480, A198647.
%K A198687 nonn,easy
%O A198687 0,1
%A A198687 _Vincenzo Librandi_, Oct 29 2011