Product_{n>=1} (1 + x^n)^a(n) = 1 + Sum_{n>=1} mu(n)*x^n, where mu = A008683.

Terms

a(0) =1a(1) =-1a(2) =0a(3) =-1a(4) =-1a(5) =2a(6) =-4a(7) =4a(8) =-7a(9) =8a(10) =-10a(11) =9a(12) =-5a(13) =-6a(14) =19a(15) =-40a(16) =70a(17) =-110a(18) =138a(19) =-158a(20) =154a(21) =-93a(22) =-70a(23) =355a(24) =-797a(25) =1408a(26) =-2160a(27) =2925a(28) =-3479a(29) =3399