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 A085952 #18 Jun 12 2025 17:10:08
%S A085952 1,91,901,9001,90001,900001,9000001,90000001,900000001,9000000001,
%T A085952 90000000001,900000000001,9000000000001,90000000000001,
%U A085952 900000000000001,9000000000000001,90000000000000001,900000000000000001,9000000000000000001,90000000000000000001,900000000000000000001
%N A085952 First n-digit number that occurs in the sequence A085951.
%H A085952 Vincenzo Librandi, <a href="/A085952/b085952.txt">Table of n, a(n) for n = 0..1000</a>
%H A085952 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A085952 For n > 0, a(n) = 9*10^n + 1. - _David Wasserman_, Feb 15 2005
%F A085952 From _Elmo R. Oliveira_, Jun 12 2025: (Start)
%F A085952 G.f.: (1 + 80*x - 90*x^2)/((10*x-1)*(x-1)).
%F A085952 E.g.f.: exp(x)*(1 + 9*exp(9*x)) - 9.
%F A085952 a(n) = 11*a(n-1) - 10*a(n-2) for n >= 3. (End)
%t A085952 Join[{1},Table[9*10^n+1,{n,30}]] (* or *) LinearRecurrence[{11,-10},{1,91,901},30] (* _Harvey P. Dale_, Dec 19 2022 *)
%o A085952 (Magma) [1] cat [9*10^n+1: n in [1..30]]; // _Vincenzo Librandi_, Nov 09 2011
%Y A085952 Cf. A085951.
%K A085952 nonn,easy,base
%O A085952 0,2
%A A085952 _Amarnath Murthy_ and _Jason Earls_, Jul 15 2003
%E A085952 Corrected and extended by _David Wasserman_, Feb 15 2005