Primes consisting only of digits 6 and 7 occurring with equal frequency.

Terms

a(0) =67a(1) =67766767a(2) =76767667a(3) =6666767777a(4) =6667677677a(5) =6667776767a(6) =6667777667a(7) =6676766777a(8) =6676767677a(9) =6676776677a(10) =6677666777a(11) =6677667767a(12) =6677676767a(13) =6766677767a(14) =6766776677a(15) =6767667677a(16) =6767677667a(17) =6776766677a(18) =6776766767a(19) =6776767667a(20) =6777667667a(21) =7666677677a(22) =7666767677a(23) =7667676677