a(n) = n! / Product_{p prime < n}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =4a(5) =20a(6) =24a(7) =168a(8) =192a(9) =1728a(10) =17280a(11) =190080a(12) =207360a(13) =2695680a(14) =2903040a(15) =43545600a(16) =696729600a(17) =11844403200a(18) =12541132800a(19) =238281523200a(20) =250822656000