E.g.f.: Product_{k>0} (1+x^k)^(-1/k).

Terms

a(0) =1a(1) =-1a(2) =1a(3) =-5a(4) =23a(5) =-119a(6) =619a(7) =-4759a(8) =48145a(9) =-476657a(10) =4249961a(11) =-48286061a(12) =691331431a(13) =-9132207655a(14) =117900772963