a(n) = (number of digits <=1) - (number of digits >1) in base 4 representation of n.

Terms

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