Exactly 4 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a prime.

Terms

a(0) =11a(1) =19a(2) =27a(3) =31a(4) =41a(5) =47a(6) =53a(7) =67a(8) =73a(9) =87a(10) =91a(11) =97a(12) =109a(13) =129a(14) =151a(15) =153a(16) =187a(17) =203a(18) =209a(19) =217a(20) =231a(21) =243a(22) =273a(23) =283a(24) =311a(25) =323a(26) =373a(27) =389a(28) =423a(29) =433