%I #2 Mar 30 2012 18:50:59
%S 4,4,4,4,5,5,6,6,6,7,7,8,8,8,9,9,9,10,10,11,11,11,12,12,12,13,13,13,
%T 14,14,14,15,15,15,16,16,16,17,17,17,17,18,18,18,19,19,19,20,20,20,21,
%U 21,21,21,22,22,22,23,23,23,24,24,24,24,25,25,25,26,26,26,26,27,27,27,28
%N Floor(8*n/(5*log(n))).
%C A138194(n) <= A000720(n) <= a(n), (Tschebyscheff, 1850).
%Y Cf. A050500, A050499, A050501.
%K nonn
%O 2,1
%A _Reinhard Zumkeller_, Mar 04 2008