Number of primes < 9^n.

Terms

a(0) =0a(1) =4a(2) =22a(3) =129a(4) =847a(5) =5968a(6) =43934a(7) =334349a(8) =2607165a(9) =20700806a(10) =166677978a(11) =1357200840a(12) =11152818693a(13) =92349038518a(14) =769616513836