Nonprime lucky numbers.

Terms

a(0) =1a(1) =9a(2) =15a(3) =21a(4) =25a(5) =33a(6) =49a(7) =51a(8) =63a(9) =69a(10) =75a(11) =87a(12) =93a(13) =99a(14) =105a(15) =111a(16) =115a(17) =129a(18) =133a(19) =135a(20) =141a(21) =159a(22) =169a(23) =171a(24) =189a(25) =195a(26) =201a(27) =205a(28) =219a(29) =231