a(n) = ceiling(n!/d(n!)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =24a(6) =84a(7) =420a(8) =2268a(9) =13440a(10) =73920a(11) =604800a(12) =3931200a(13) =33633600a(14) =324324000a(15) =3891888000a(16) =33081048000a(17) =435891456000