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 A161770 #19 Jun 19 2025 00:28:19
%S A161770 1000,11000,111000,1111000,11111000,111111000,1111111000,11111111000,
%T A161770 111111111000,1111111111000,11111111111000,111111111111000,
%U A161770 1111111111111000,11111111111111000,111111111111111000,1111111111111111000,11111111111111111000,111111111111111111000
%N A161770 n 1's followed by three 0's.
%C A161770 Sequence A159741 written in base 2.
%H A161770 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A161770 a(n) = 1000*(10^n - 1)/9 = 1000*A002275(n).
%F A161770 G.f.: 1000*x/((10*x-1)*(x-1)).
%F A161770 From _Elmo R. Oliveira_, Jun 18 2025: (Start)
%F A161770 E.g.f.: 1000*exp(x)*(exp(9*x) - 1)/9.
%F A161770 a(n) = 100*A105279(n) = 10*A124166(n).
%F A161770 a(n) = 11*a(n-1) - 10*a(n-2) for n > 2. (End)
%t A161770 Table[FromDigits[PadLeft[{0,0,0},n,1]],{n,4,20}] (* _Harvey P. Dale_, Aug 07 2023 *)
%Y A161770 Cf. A002275, A105279, A124166, A159741.
%K A161770 nonn,easy,base
%O A161770 1,1
%A A161770 _Jaroslav Krizek_, Jun 18 2009
%E A161770 Edited by _Charles R Greathouse IV_, Oct 12 2009