Numbers k such that k surrounded by digit '9' is a prime.

Terms

a(0) =1a(1) =2a(2) =10a(3) =19a(4) =20a(5) =23a(6) =31a(7) =34a(8) =41a(9) =43a(10) =47a(11) =53a(12) =61a(13) =62a(14) =64a(15) =67a(16) =68a(17) =71a(18) =73a(19) =74a(20) =76a(21) =82a(22) =83a(23) =85a(24) =92a(25) =94a(26) =100a(27) =101a(28) =107a(29) =109