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A055729 Number of primes <= 3^n. 9
0, 2, 4, 9, 22, 53, 129, 327, 847, 2227, 5968, 16097, 43934, 120739, 334349, 931260, 2607165, 7332159, 20700806, 58648288, 166677978, 475023803, 1357200840, 3886548158, 11152818693, 32064929886, 92349038518, 266398236486, 769616513836, 2226457080707, 6449247674296, 18703411700669, 54301968156067, 157820174545456 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Henri Lifchitz, Table of n, a(n) for n = 0..49

Index entries for sequences related to numbers of primes in various ranges

FORMULA

a(n) = A000720(A000244(n)). - Michel Marcus, Aug 25 2014

MATHEMATICA

Table[PrimePi[3^n], {n, 0, 29}]

PROG

(PARI) a(n) = primepi(3^n); \\ Michel Marcus, Aug 25 2014

CROSSREFS

Cf. A006880 and A007053.

Sequence in context: A057580 A129875 A055094 * A238826 A048211 A098719

Adjacent sequences:  A055726 A055727 A055728 * A055730 A055731 A055732

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Jun 09 2000

EXTENSIONS

a(28)-a(40) from Henri Lifchitz, Nov 11 2012

STATUS

approved

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Last modified August 28 05:09 EDT 2015. Contains 261118 sequences.