G.f. A(x) satisfies: A(x) = x * Product_{k>=1} 1/(1 - A(x^k))^k.

Terms

a(0) =1a(1) =1a(2) =4a(3) =12a(4) =41a(5) =133a(6) =485a(7) =1752a(8) =6677a(9) =25809a(10) =102130a(11) =409532a(12) =1665128a(13) =6837348a(14) =28333334a(15) =118288386a(16) =497120101a(17) =2101181482a(18) =8926401690a(19) =38093403136a(20) =163224292328a(21) =701951448268