%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
%C such that pi(n)=(1/10^m)*n is a finite set. I guess that all these sets are
%C nonempty. What is the smallest number n such that pi(n)=(1/100)*n?
%t Select[10 Range, PrimePi[ # ] == 1/10 # &]
%Y Cf. A057809,
%A _Farideh Firoozbakht_, Oct 06 2009