G.f.: s(1)^3/s(3), where s(k) = eta(q^k) and eta(q) is Dedekind's function, cf. A010815.

Terms

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