a(n)=(number of digits <=2)-(number of digits >2) in base 6 representation of n.

Terms

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