Primes that contain digits 6 and 7 only.

Terms

a(0) =7a(1) =67a(2) =677a(3) =67777a(4) =76667a(5) =76777a(6) =666667a(7) =677767a(8) =767677a(9) =777677a(10) =6676667a(11) =6676777a(12) =6677677a(13) =6677767a(14) =6677777a(15) =6766667a(16) =6766777a(17) =6776677a(18) =7666667a(19) =7667677a(20) =7667767a(21) =7766767a(22) =7766777a(23) =7777667a(24) =66666667a(25) =66677777a(26) =66776777a(27) =67667777a(28) =67766767a(29) =67776677