Palindromic primes using only two distinct digits and only the exterior digit is different.

Terms

a(0) =101a(1) =131a(2) =151a(3) =181a(4) =191a(5) =313a(6) =353a(7) =373a(8) =383a(9) =727a(10) =757a(11) =787a(12) =797a(13) =919a(14) =929a(15) =13331a(16) =15551a(17) =16661a(18) =19991a(19) =72227a(20) =75557a(21) =76667a(22) =78887a(23) =79997a(24) =1333331a(25) =1444441a(26) =1777771a(27) =3222223a(28) =3444443a(29) =7666667