a(1) = 1, a(2) = -9; a(n) = -n^3 * Sum_{d|n, d < n} a(d) / d^3.

Terms

a(0) =1a(1) =-9a(2) =-27a(3) =8a(4) =-125a(5) =243a(6) =-343a(7) =0a(8) =0a(9) =1125a(10) =-1331a(11) =-216a(12) =-2197a(13) =3087a(14) =3375a(15) =0a(16) =-4913a(17) =0a(18) =-6859a(19) =-1000a(20) =9261a(21) =11979a(22) =-12167a(23) =0a(24) =0a(25) =19773a(26) =0a(27) =-2744a(28) =-24389a(29) =-30375