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 A088697 #8 Dec 05 2023 15:40:43
%S A088697 0,1,6,3,26,13,14,7,106,53,54,27,58,29,30,15,426,213,214,107,218,109,
%T A088697 110,55,234,117,118,59,122,61,62,31,1706,853,854,427,858,429,430,215,
%U A088697 874,437,438,219,442,221,222,111,938,469,470,235,474,237
%N A088697 Replace 0 with 10 in binary representation of n.
%H A088697 Rémy Sigrist, <a href="/A088697/b088697.txt">Table of n, a(n) for n = 0..8192</a>
%F A088697 a(0)=0, a(2n) = 4a(n) + 2, a(2n+1) = 2a(n) + 1.
%e A088697 n=9: 1001 -> 110101 = 53, so a(9) = 53.
%t A088697 Join[{0},Table[FromDigits[Flatten[IntegerDigits[n,2]/.(0->{1,0})],2],{n,80}]] (* _Harvey P. Dale_, Dec 05 2023 *)
%o A088697 (PARI) a(n)=if(n<1,0,if(n%2==0,4*a(n/2)+2,2*a((n-1)/2)+1))
%Y A088697 Cf. A084471, A048678, A088698.
%K A088697 nonn,easy,base
%O A088697 0,3
%A A088697 _Ralf Stephan_, Oct 07 2003