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A234317 Number of primes <= R_n where R_n is 11...111 with n 1's. 0
0, 5, 29, 186, 1345, 10544, 86537, 733409, 6363181, 56196113, 503193256, 4555800188, 41621368073, 383118399785, 3549047966156 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..15.

FORMULA

a(n) = A000720(R_n) = A000720(A002275(n)) where R_n is 11...111 with n 1's.

EXAMPLE

There are 1345 primes less than or equal to 11111. Thus a(5) = 1345.

MATHEMATICA

PrimePi/@Table[FromDigits[PadRight[{}, n, 1]], {n, 15}] (* The program will take a long time to run *) (* Harvey P. Dale, Jan 21 2015 *)

PROG

(Python)

import sympy

from sympy import primepi

for n in range(1, 50):

..print(primepi((10**n-1)/9), end=', ')

(PARI) a(n)=primepi(10^n\9) \\ Charles R Greathouse IV, Apr 30 2014

CROSSREFS

Cf. A000720, A002275.

Sequence in context: A127846 A059231 A137573 * A078945 A113713 A142980

Adjacent sequences:  A234314 A234315 A234316 * A234318 A234319 A234320

KEYWORD

nonn,more,less

AUTHOR

Derek Orr, Dec 23 2013

EXTENSIONS

a(14)-a(15) from Hiroaki Yamanouchi, Sep 27 2014

STATUS

approved

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Last modified March 20 07:27 EDT 2019. Contains 321345 sequences. (Running on oeis4.)