OFFSET
1,2
LINKS
David Baugh, Table of n, a(n) for n = 1..26 (terms n = 16..26 found with Kim Walisch's primecount program).
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
KEYWORD
nonn,less
AUTHOR
Derek Orr, Dec 23 2013
EXTENSIONS
a(14)-a(15) from Hiroaki Yamanouchi, Sep 27 2014
a(16)-a(22) from David Baugh, Sep 29 2020
STATUS
approved