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 A173736 #15 Jun 18 2025 18:05:19
%S A173736 5,15,115,1115,11115,111115,1111115,11111115,111111115,1111111115,
%T A173736 11111111115,111111111115,1111111111115,11111111111115,
%U A173736 111111111111115,1111111111111115,11111111111111115,111111111111111115,1111111111111111115,11111111111111111115,111111111111111111115
%N A173736 a(n) = (10^n + 35)/9 for n>0.
%H A173736 Vincenzo Librandi, <a href="/A173736/b173736.txt">Table of n, a(n) for n = 1..100</a>
%H A173736 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A173736 a(n) = a(n-1) + 10^(n-1) = 10*a(n-1) - 35 with n>0, a(0)=4.
%F A173736 From _Vincenzo Librandi_, Jul 05 2012: (Start)
%F A173736 G.f.: 5*x*(1-8*x)/((1-x)*(1-10*x)).
%F A173736 a(n) = 11*a(n-1) - 10*a(n-2). (End)
%F A173736 From _Elmo R. Oliveira_, Jun 18 2025: (Start)
%F A173736 E.g.f.: -4 + exp(x)*(35 + exp(9*x))/9.
%F A173736 a(n) = 5*A093135(n-1). (End)
%t A173736 CoefficientList[Series[(5-40*x)/((1-x)*(1-10*x)),{x,0,30}],x] (* _Vincenzo Librandi_, Jul 05 2012 *)
%o A173736 (Magma) [(10^n+35)/9: n in [1..20]]; // _Vincenzo Librandi_, Jul 05 2012
%Y A173736 Cf. A093135.
%K A173736 nonn,easy
%O A173736 1,1
%A A173736 _Vincenzo Librandi_, Feb 23 2010