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 A137893 #11 Nov 10 2021 01:16:38
%S A137893 1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,0,0,1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,
%T A137893 0,1,1,0,1,1,0,0,1,0,0,1,0,1,1,0,0,1,0,0,1,0,1,1,0,0,1,0,1,1,0,1,1,0,
%U A137893 0,1,0,0,1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,0,1,1,0,1,1,0,0,1,0,0,1,0,1,1,0,0
%N A137893 Fixed point of the morphism 0->100, 1->101, starting from a(1) = 1.
%C A137893 Similar to A080846, but with the 1's and 0's interchanged.
%C A137893 A generalized choral sequence c(3n+r_0)=0, c(3n+r_1)=1, c(3n+r_c)=c(n), with r_0=1, r_1=0, and r_c=2. [From Joel Reyes Noche (joel.noche(AT)up.edu.ph), Jul 09 2009]
%D A137893 J. R. Noche, Generalized Choral Sequences, Matimyas Matematika, 31(2008), 25-28. [From Joel Reyes Noche (joel.noche(AT)up.edu.ph), Jul 09 2009]
%H A137893 Michael De Vlieger, <a href="/A137893/b137893.txt">Table of n, a(n) for n = 1..6561</a>
%t A137893 Flatten[Nest[#/.{0->{1,0,0},1->{1,0,1}}&,1,5]] (* _Harvey P. Dale_, Jul 29 2015 *)
%o A137893 (PARI) a(n) = my(r); until(r,[n,r]=divrem(n,3)); 2-r; \\ _Kevin Ryde_, Nov 09 2021
%Y A137893 Cf. A080846 (complement), A060236 (as 1,2), A343785 (as +-1).
%Y A137893 Cf. A026179 (indices of 0's except n=1), A189674 (partial sums).
%K A137893 easy,nonn
%O A137893 1,1
%A A137893 Joel Reyes Noche (joel.noche(AT)up.edu.ph), Apr 30 2008