Digit '6' concatenated with n is a prime.

Terms

a(0) =1a(1) =7a(2) =13a(3) =17a(4) =19a(5) =31a(6) =41a(7) =43a(8) =47a(9) =53a(10) =59a(11) =61a(12) =73a(13) =77a(14) =83a(15) =91a(16) =101a(17) =113a(18) =121a(19) =131a(20) =133a(21) =143a(22) =151a(23) =163a(24) =173a(25) =197a(26) =199a(27) =203a(28) =211a(29) =217