a(n) = (greatest base 4 digit of n) - (least base 4 digit of n).

Terms

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