Product of digits is noncomposite.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =11a(7) =12a(8) =13a(9) =15a(10) =17a(11) =21a(12) =31a(13) =51a(14) =71a(15) =111a(16) =112a(17) =113a(18) =115a(19) =117a(20) =121a(21) =131a(22) =151a(23) =171a(24) =211a(25) =311a(26) =511a(27) =711a(28) =1111a(29) =1112