%I #4 Mar 31 2012 14:40:18

%S 0,50,75,75,75,78,78,77,75,72,70,66,64,61,59,57,55,53,51,49,48,46,45,

%T 43,42,41,40,39,38,37,36,35,34

%N Percentage (rounded) of odd numbers < 2^n which are primes or squarefree semiprimes.

%F a(n) = round((A146168(n)+A007053(n)-1)/(2^(n-1))*100).

%e a(4)=75 because 75% of the 2^3 numbers 1, 3, 5, 7, 9, 11, 13 and 15 are primes or squarefree semiprimes.

%Y Cf. A001358(semiprimes), A007053(Number of primes <= 2^n), A146168(Number of odd squarefree semiprimes < 2^n).

%K nonn

%O 1,2

%A _Washington Bomfim_, Oct 27 2008