a(3n) = n, a(3n+1) = (n+2)*a(3n), a(3n+2) = (n+2)*a(3n+1).

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =9a(6) =2a(7) =8a(8) =32a(9) =3a(10) =15a(11) =75a(12) =4a(13) =24a(14) =144a(15) =5a(16) =35a(17) =245a(18) =6a(19) =48a(20) =384a(21) =7a(22) =63a(23) =567a(24) =8a(25) =80a(26) =800a(27) =9a(28) =99a(29) =1089