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 A102397 #4 May 15 2016 10:25:23
%S A102397 1,10,100,1001,10010,100101,1001011,10010110,100101100,1001011001,
%T A102397 10010110011,100101100110,1001011001101,10010110011010,
%U A102397 100101100110100,1001011001101001,10010110011010010,100101100110100101
%N A102397 a(n) = concatenation of first n elements of Thue-Morse sequence A010059.
%F A102397 a(n)=sum{k=0..n, (1+(-1)^A010060(n-k))10^k/2}.
%t A102397 With[{tm=Nest[Join[#,Mod[2#+1,3]]&,{1},10]},Table[FromDigits[Take[tm,n]],{n,20}]] (* _Harvey P. Dale_, May 15 2016 *)
%Y A102397 Cf. A019299.
%K A102397 base,easy,nonn
%O A102397 0,2
%A A102397 _Paul Barry_, Jan 06 2005