"Trim" numbers that are not prime; see reference for definition.

Terms

a(0) =27a(1) =125a(2) =147a(3) =189a(4) =539a(5) =625a(6) =875a(7) =1029a(8) =1925a(9) =2025a(10) =2187a(11) =2499a(12) =3159a(13) =3249a(14) =3757a(15) =4125a(16) =4199a(17) =4719a(18) =4851a(19) =5145a(20) =5733a(21) =5775a(22) =6517a(23) =6561a(24) =6615a(25) =7203a(26) =8415a(27) =8775a(28) =10005a(29) =10125