Digit '1' concatenated with a(n) is a prime.

Terms

a(0) =1a(1) =3a(2) =7a(3) =9a(4) =13a(5) =27a(6) =31a(7) =37a(8) =39a(9) =49a(10) =51a(11) =57a(12) =63a(13) =67a(14) =73a(15) =79a(16) =81a(17) =91a(18) =93a(19) =97a(20) =99a(21) =103a(22) =109a(23) =117a(24) =123a(25) =129a(26) =151a(27) =153a(28) =163a(29) =171