G.f.: 1 + Sum_{n=-oo..+oo, n<>0} (x - x^n)^n / (1 - (x - x^n)^n).

Terms

a(0) =1a(1) =-1a(2) =2a(3) =-3a(4) =7a(5) =-11a(6) =17a(7) =-21a(8) =35a(9) =-67a(10) =125a(11) =-179a(12) =246a(13) =-384a(14) =715a(15) =-1199a(16) =1871a(17) =-2850a(18) =4593a(19) =-7589a(20) =12811a(21) =-20366a(22) =31545a(23) =-50483a(24) =84597a(25) =-138964a(26) =222534a(27) =-352910a(28) =569680a(29) =-931694