(Product{k|n} k$) / n$. Here '$' denotes the swinging factorial function (A056040).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =12a(7) =1a(8) =12a(9) =6a(10) =60a(11) =1a(12) =1440a(13) =1a(14) =280a(15) =180a(16) =840a(17) =1a(18) =151200a(19) =1a(20) =90720a(21) =840a(22) =5544a(23) =1a(24) =93139200a(25) =30a(26) =24024a(27) =3780a(28) =5765760a(29) =1