Number of primes < 6^n.

Terms

a(0) =0a(1) =3a(2) =11a(3) =47a(4) =210a(5) =985a(6) =4821a(7) =24427a(8) =126726a(9) =669432a(10) =3588148a(11) =19453038a(12) =106460872a(13) =587176205a(14) =3259873268a(15) =18200088376a(16) =102107048666a(17) =575281018454