From Euler's Pentagonal Theorem: coefficient of q^n in Product_{m>=1} (1 - q^m).

Terms

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