Smallest prime > 2n+1 beginning and ending with 2n+1, or 0 if no such prime exists.

Terms

a(0) =11a(1) =313a(2) =0a(3) =727a(4) =919a(5) =11311a(6) =13313a(7) =0a(8) =17117a(9) =19219a(10) =21121a(11) =23623a(12) =0a(13) =27127a(14) =29129a(15) =31231a(16) =33533a(17) =0a(18) =37337a(19) =39139a(20) =41141a(21) =43543a(22) =0a(23) =47147a(24) =49549a(25) =51151a(26) =53353a(27) =0a(28) =57457a(29) =59159