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 A030315 #31 Feb 16 2025 08:32:35
%S A030315 1,0,0,1,0,0,0,1,1,0,1,0,0,0,1,0,0,0,0,1,1,1,0,1,1,0,0,1,0,1,0,1,0,0,
%T A030315 0,0,1,1,0,0,1,0,0,0,0,1,0,0,0,0,0,1,1,1,1,0,1,1,1,0,0,1,1,0,1,0,1,1,
%U A030315 0,0,0,1,0,1,1,0,1,0,1,0,0,1,0,0,1,0,1,0,0,0,0
%N A030315 Write n in base 2, complement each digit (d -> 1-d) and append the complemented digits to the sequence.
%H A030315 Harvey P. Dale, <a href="/A030315/b030315.txt">Table of n, a(n) for n = 0..1000</a>
%H A030315 Eric W. Weisstein, <a href="https://mathworld.wolfram.com/ChampernowneConstant.html">Champernowne Constant</a>.
%F A030315 a(n) = 1 - A030190(n). - _Amiram Eldar_, May 22 2023
%e A030315 To get the initial terms:
%e A030315 0 -> 1
%e A030315 1 -> 0
%e A030315 2 = 10 -> 0, 1
%e A030315 3 = 11 -> 0, 0
%e A030315 4 = 100 -> 0, 0, 1
%e A030315 5 = 101 -> 0, 1, 0,
%e A030315 ...
%e A030315 and concatenating 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, ... gives the start of the sequence. - _N. J. A. Sloane_, Jan 30 2023
%t A030315 Table[IntegerDigits[n,2]/.{1->0,0->1},{n,0,30}]//Flatten (* _Harvey P. Dale_, Jan 30 2023 *)
%Y A030315 Cf. A030190, A180433. [_Jonathan Vos Post_, Sep 05 2010]
%K A030315 nonn,base
%O A030315 0,1
%A A030315 _Clark Kimberling_
%E A030315 a(0)=1 added by _Jonathan Vos Post_, Sep 05 2010
%E A030315 Edited by _N. J. A. Sloane_, Jan 30 2023