a(0) = 0; a(n) = a(n/4)/4 if n = a(n/4) = 0 (mod 4); a(n) = a(n-1)+1 otherwise.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =5a(6) =6a(7) =7a(8) =8a(9) =9a(10) =10a(11) =11a(12) =12a(13) =13a(14) =14a(15) =15a(16) =1a(17) =2a(18) =3a(19) =4a(20) =5a(21) =6a(22) =7a(23) =8a(24) =9a(25) =10a(26) =11a(27) =12a(28) =13a(29) =14