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

Terms

a(0) =0a(1) =2a(2) =6a(3) =2a(4) =120a(5) =8a(6) =5040a(7) =2a(8) =6a(9) =122a(10) =39916800a(11) =8a(12) =6227020800a(13) =5042a(14) =126a(15) =2a(17) =8a(19) =122a(20) =5046a(21) =39916802a(23) =8a(24) =120a(25) =6227020802a(26) =6a(27) =5042a(29) =128