a(n) = Sum_{d|n} Kronecker(-18, d).

Terms

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