A086681 Number of primes < 8^n.

0, 4, 18, 97, 564, 3512, 23000, 155611, 1077871, 7603553, 54400028, 393615806, 2874398515, 21151907950, 156661034233, 1166746786182, 8731188863470, 65612899915304, 494890204904784, 3745011184713964, 28423094496953330, 216289611853439384, 1649819700464785589

Offset: 0

Author

Cino Hilliard, Jul 28 2003

Keywords

• nonn

Links

• David Baugh, Table of n, a(n) for n = 0..30 (terms m = 29..30 found using Kim Walisch's primecount program)

Crossrefs

Cf. A000720, A185192.

Programs

Magma

[#PrimesUpTo(8^n): n in [0..9]]; // Vincenzo Librandi, Mar 26 2017

Mathematica

PrimePi/@(8^Range[0,14])  (* Harvey P. Dale, Mar 13 2011 *)
Table[PrimePi[8^n], {n, 0, 15}] (* Vincenzo Librandi, Mar 26 2017 *)

Formula

a(n) = A185192(3n). - R. J. Mathar, Sep 15 2012

Extensions

More terms from Harvey P. Dale, Mar 13 2011

a(15)-a(16) from Vincenzo Librandi, Mar 26 2017

a(17)-a(22) from David Baugh, Oct 08 2020