a(n) = A003418(n)/A000793(n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =10a(6) =10a(7) =35a(8) =56a(9) =126a(10) =84a(11) =924a(12) =462a(13) =6006a(14) =4290a(15) =3432a(16) =5148a(17) =58344a(18) =58344a(19) =554268a(20) =554268a(21) =554268a(22) =554268a(23) =6374082a(24) =6374082a(25) =21246940a(26) =21246940a(27) =52151580a(28) =34767720a(29) =924241890