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 A125720 #7 Dec 22 2024 14:28:25
%S A125720 0,1,1,0,0,0,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,1,1,0,0,0,1,0,1,
%T A125720 1,0,0,0,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,0,0,1,1,1,0
%N A125720 A variation on the Thue-Morse sequence.
%H A125720 James C. McMahon, <a href="/A125720/b125720.txt">Table of n, a(n) for n = 1..1024</a>
%e A125720 Start with chain 1 equal to 0:
%e A125720 ch 1 = 0
%e A125720 Copy and paste chain 1, then complement 1 rightmost digit (1->0, 0->1):
%e A125720 ch 2 = 0,1
%e A125720 Copy and paste chain 2, then complement 2 rightmost digits (1->0, 0->1):
%e A125720 ch 3 = 0,1,1,0
%e A125720 Copy and paste chain 3, then complement 3 rightmost digits (1->0, 0->1):
%e A125720 ch 4 = 0,1,1,0,0,0,0,1
%e A125720 Copy and paste chain 4, then complement 4 rightmost digits (1->0, 0->1):
%e A125720 ch 5 = 0,1,1,0,0,0,0,1,0,1,1,0,1,1,1,0
%e A125720 Copy and paste chain 5, then complement 5 rightmost digits (1->0, 0->1):
%e A125720 ch 6 = 0,1,1,0,0,0,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,1,1,0,0,0,1
%e A125720 Copy and paste chain 6, then complement 6 rightmost digits (1->0, 0->1):
%e A125720 ch 7 = 0,1,1,0,0,0,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,1,1,0,0,0,1,0,1,1,0,0,0,0,1,0,1,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,0,0,1,1,1,0
%e A125720 etc.
%t A125720 s={0};Do[s=Join[s,s];a=Take[s,-n]/.{0->1,1->0};s=Join[Drop[s,-n],a],{n,6}];s (* _James C. McMahon_, Dec 22 2024 *)
%Y A125720 Cf. A010060.
%K A125720 easy,nonn
%O A125720 1,1
%A A125720 _Eric Angelini_, Feb 01 2007