a(n) is the least strongly refactorable multiple of n if any, or a(n) = -1 otherwise.

Terms

a(0) =1a(1) =2a(2) =12a(3) =12a(4) =240a(5) =12a(6) =3360a(7) =24a(8) =36a(9) =240a(10) =5280a(11) =12a(12) =6240a(13) =3360a(14) =240a(15) =240a(16) =8160a(17) =36a(18) =9120a(19) =240a(20) =3360a(21) =5280a(22) =11040a(23) =24a(24) =21600a(25) =6240a(26) =4320a(27) =3360a(28) =13920a(29) =240