A055731 Number of primes < 6^n.

0, 3, 11, 47, 210, 985, 4821, 24427, 126726, 669432, 3588148, 19453038, 106460872, 587176205, 3259873268, 18200088376, 102107048666, 575281018454, 3253321522134, 18459252891532, 105048100696856, 599403542263094, 3428437672359713, 19652744592040804, 112879982373565581, 649538196329702877, 3743885544339750283, 21612949469350359942, 124947894360104092955

Offset: 0

Author

Robert G. Wilson v, Jun 09 2000

Keywords

• nonn

Links

• David Baugh, Table of n, a(n) for n = 0..33 (terms n = 29..33 found using Kim Walisch's primecount program)
• Index entries for sequences related to numbers of primes in various ranges

Crossrefs

Cf. A006880, A007053 and A040014.

Cf. A000400, A000720.

Programs

Mathematica

Table[PrimePi[6^n], {n, 0, 17}]

PARI

a(n) = primepi(6^n); \\ Michel Marcus, Oct 05 2020

Formula

a(n) = A000720(A000400(n)). - Michel Marcus, Oct 05 2020

Extensions

a(18)-a(24) from Henri Lifchitz, Nov 11 2012

a(25)-a(28) from Henri Lifchitz, Aug 25 2014