Palindromic primes in bases 2 and 4.

Terms

a(0) =3a(1) =5a(2) =17a(3) =257a(4) =5189a(5) =65537a(6) =83269a(7) =86293a(8) =1053953a(9) =1066049a(10) =1134929a(11) =1311749a(12) =1380629a(13) =16864513a(14) =17060929a(15) =17909009a(16) =18153809a(17) =18171217a(18) =21251141a(19) =22103317a(20) =289423441a(21) =290455889a(22) =290735441a(23) =336662789a(24) =336925957a(25) =340873541