%N Numbers n such that pi(n) = (1/10)*n.
%C A subsequence of A057809. For each positive integer m, set of the numbers n such that pi(n)=(1/10^m)*n is a finite set. I guess that all these sets are nonempty. What is the smallest number n such that pi(n) = (1/100)*n?
%t Select[10 Range, PrimePi[ # ] == 1/10 # &]
%o (PARI) forcomposite(n=1, 1e5, if(10*primepi(n) == n, print1(n, ", "))) \\ _Altug Alkan_, Dec 18 2015
%Y Cf. A057809.
%A _Farideh Firoozbakht_, Oct 06 2009