A146170 Percentage (rounded) of odd numbers < 2^n which are primes or squarefree semiprimes.

0, 50, 75, 75, 75, 78, 78, 77, 75, 72, 70, 66, 64, 61, 59, 57, 55, 53, 51, 49, 48, 46, 45, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34

Offset: 1

Author

Washington Bomfim, Oct 27 2008

Keywords

• nonn

Examples

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

Crossrefs

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

Formula

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