%I #16 Feb 20 2021 23:11:06

%S 0,3,6,15,12,27,30,63,24,51,54,111,60,123,126,255,48,99,102,207,108,

%T 219,222,447,120,243,246,495,252,507,510,1023,96,195,198,399,204,411,

%U 414,831,216,435,438,879,444,891,894,1791,240,483,486,975,492,987,990

%N Replace 1 with 11 in binary representation of n.

%H Rémy Sigrist, <a href="/A088698/b088698.txt">Table of n, a(n) for n = 0..8192</a>

%F a(0)=0, a(2n) = 2a(n), a(2n+1) = 4a(n) + 3.

%e n=9: 1001 -> 110011 = 51, so a(9) = 51.

%o (PARI) a(n)=if(n<1,0,if(n%2==0,2*a(n/2),4*a((n-1)/2)+3))

%o (Python)

%o def a(n): return int(bin(n)[2:].replace('1', '11'), 2)

%o print([a(n) for n in range(55)]) # _Michael S. Branicky_, Feb 20 2021

%Y Ordered terms plus one are in A048297.

%Y Same sequence sorted into ascending order: A277335, A290258 (without 0).

%Y Cf. A001196, A084471, A048678, A088697.

%Y Main diagonal of A341520, right edge of A341521.

%K nonn,easy,base

%O 0,2

%A _Ralf Stephan_, Oct 07 2003