Numbers such that, in base 10, all their proper prefixes and suffixes represent primes.

Terms

a(0) =22a(1) =23a(2) =25a(3) =27a(4) =32a(5) =33a(6) =35a(7) =37a(8) =52a(9) =53a(10) =55a(11) =57a(12) =72a(13) =73a(14) =75a(15) =77a(16) =237a(17) =297a(18) =313a(19) =317a(20) =373a(21) =537a(22) =597a(23) =713a(24) =717a(25) =737a(26) =797a(27) =2337a(28) =2397a(29) =2937