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 A198691 #18 Sep 08 2022 08:45:59
%S A198691 9,69,489,3429,24009,168069,1176489,8235429,57648009,403536069,
%T A198691 2824752489,19773267429,138412872009,968890104069,6782230728489,
%U A198691 47475615099429,332329305696009,2326305139872069,16284135979104489,113988951853731429
%N A198691 10*7^n-1.
%H A198691 Vincenzo Librandi, <a href="/A198691/b198691.txt">Table of n, a(n) for n = 0..1000</a>
%H A198691 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (8,-7).
%F A198691 a(n) = 7*a(n-1)+6. a(n) = 8*a(n-1)-7*a(n-2), n>1.
%F A198691 G.f. ( 9-3*x ) / ( (7*x-1)*(x-1) ). - R. J. Mathar, Oct 30 2011
%t A198691 10*7^Range[0,20]-1 (* or *) LinearRecurrence[{8,-7},{9,69},20] (* _Harvey P. Dale_, Mar 30 2016 *)
%o A198691 (Magma) [10*7^n-1: n in [0..30]]
%Y A198691 Cf. A024075, A048473, A081655, A198480, A198647.
%K A198691 nonn,easy
%O A198691 0,1
%A A198691 _Vincenzo Librandi_, Oct 29 2011