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 A171553 #26 Sep 06 2024 17:02:22
%S A171553 11,191,10901,1009001,100090001,10000900001,1000009000001,
%T A171553 100000090000001,10000000900000001,1000000009000000001,
%U A171553 100000000090000000001,10000000000900000000001,1000000000009000000000001,100000000000090000000000001,10000000000000900000000000001
%N A171553 a(n) = 9*10^n + 100^n + 1.
%H A171553 Vincenzo Librandi, <a href="/A171553/b171553.txt">Table of n, a(n) for n = 0..100</a>
%H A171553 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
%F A171553 G.f.: -(1910*x^2-1030*x+11) / ((x-1)*(10*x-1)*(100*x-1)). - _Colin Barker_, Jul 29 2014
%F A171553 From _Elmo R. Oliveira_, Sep 06 2024: (Start)
%F A171553 E.g.f.: exp(x)*(9*exp(9*x) + exp(99*x) + 1).
%F A171553 a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2. (End)
%t A171553 Join[{11}, Table[FromDigits[Join[{1}, PadRight[{}, n, 0], {9}, PadRight[{}, n, 0], {1}]], {n, 0, 20}]] (* _Harvey P. Dale_, Apr 26 2013 *)
%t A171553 Table[100^n + 9 * 10^n + 1, {n, 0, 19}] (* _Alonso del Arte_, Jul 28 2014 *)
%o A171553 (Magma) [1+9*10^n+100^n: n in [0..15]]; // _Vincenzo Librandi_, Jul 29 2014
%o A171553 (PARI) Vec(-(1910*x^2-1030*x+11)/((x-1)*(10*x-1)*(100*x-1)) + O(x^100)) \\ _Colin Barker_, Jul 29 2014
%Y A171553 Cf. A100459.
%K A171553 easy,nonn
%O A171553 0,1
%A A171553 _Jason Earls_, Dec 11 2009
%E A171553 More terms from _Harvey P. Dale_, Apr 26 2013