Number of divisors of n == 1 (mod 3) minus number of divisors of n == 2 (mod 3).

Terms

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