G.f.: A(x) = x*exp( Sum_{n>=1} Sum_{d|n} A(d*x^n) / n ).

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =20a(5) =49a(6) =148a(7) =391a(8) =1167a(9) =3309a(10) =9974a(11) =29083a(12) =88851a(13) =265815a(14) =818676a(15) =2497633a(16) =7753214a(17) =23968298a(18) =75015661a(19) =234347623a(20) =738220718a(21) =2325779822a(22) =7369929088a(23) =23374281968a(24) =74451070741a(25) =237439581606a(26) =759696374373