Partial products of A004001.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =12a(6) =48a(7) =192a(8) =768a(9) =3840a(10) =23040a(11) =161280a(12) =1128960a(13) =9031680a(14) =72253440a(15) =578027520a(16) =4624220160a(17) =41617981440a(18) =416179814400