Product_{n>=1} (1+x^n)^a(n) = Sum_{k>=0} C(k)*x^k, where C(k) = A000108(k).

Terms

a(0) =1a(1) =2a(2) =3a(3) =10a(4) =25a(5) =78a(6) =245a(7) =810a(8) =2700a(9) =9250a(10) =32065a(11) =112710a(12) =400023a(13) =1432858a(14) =5170575a(15) =18784170a(16) =68635477a(17) =252088416a(18) =930138521a(19) =3446167850a(20) =12815663595a(21) =47820447026a(22) =178987624513a(23) =671825132838