Number of primes < 8^n.

Terms

a(0) =0a(1) =4a(2) =18a(3) =97a(4) =564a(5) =3512a(6) =23000a(7) =155611a(8) =1077871a(9) =7603553a(10) =54400028a(11) =393615806a(12) =2874398515a(13) =21151907950a(14) =156661034233