Palindromic primes with just two distinct prime digits.

Terms

a(0) =353a(1) =373a(2) =727a(3) =757a(4) =32323a(5) =33533a(6) =35353a(7) =72227a(8) =72727a(9) =75557a(10) =77377a(11) =3222223a(12) =3223223a(13) =3233323a(14) =3337333a(15) =3353533a(16) =3553553a(17) =3773773a(18) =7722277a(19) =7733377a(20) =7772777a(21) =322222223a(22) =322323223a(23) =323222323a(24) =323232323a(25) =323333323a(26) =333535333