a(n) = Sum_{p|n, p prime} (n/p)!.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =1a(5) =8a(6) =1a(7) =24a(8) =6a(9) =122a(10) =1a(11) =744a(12) =1a(13) =5042a(14) =126a(15) =40320a(16) =1a(17) =363600a(18) =1a(19) =3628824a(20) =5046a(21) =39916802a(22) =1a(23) =479041920a(24) =120a(25) =6227020802a(26) =362880a(27) =87178291224a(28) =1a(30) =1