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 A163664 #9 Aug 02 2017 05:02:27
%S A163664 110,10100,1001000,100010000,10000100000,1000001000000,
%T A163664 100000010000000,10000000100000000,1000000001000000000,
%U A163664 100000000010000000000,10000000000100000000000,1000000000001000000000000,100000000000010000000000000,10000000000000100000000000000
%N A163664 a(n) = 10^(2*n) + 10^n.
%C A163664 A161168(n) or A063376(n) for n >= 1 written in base 2.
%C A163664 The digits from the left to the right: a 1, (n-1) times 0, a 1, and n times 0.
%H A163664 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (110,-1000).
%F A163664 a(n) = 110*a(n-1) - 1000*a(n-2).
%F A163664 a(n) = 10*A163449(n).
%F A163664 G.f.: 10*x*(11 -200*x)/((100*x-1)*(10*x-1)).
%F A163664 E.g.f.: exp(100*x) + exp(10*x) -2. - _G. C. Greubel_, Aug 01 2017
%t A163664 LinearRecurrence[{110,-1000}, {110,10100}, 50] (* _G. C. Greubel_, Aug 01 2017 *)
%o A163664 (PARI) x='x+O('x^50); Vec(10*x*(11 -200*x)/((100*x-1)*(10*x-1))) \\ _G. C. Greubel_, Aug 01 2017
%K A163664 nonn,base,easy
%O A163664 1,1
%A A163664 _Jaroslav Krizek_, Aug 02 2009
%E A163664 Edited by _R. J. Mathar_, Aug 06 2009