This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A146170 #4 Mar 31 2012 14:40:18 %S A146170 0,50,75,75,75,78,78,77,75,72,70,66,64,61,59,57,55,53,51,49,48,46,45, %T A146170 43,42,41,40,39,38,37,36,35,34 %N A146170 Percentage (rounded) of odd numbers < 2^n which are primes or squarefree semiprimes. %F A146170 a(n) = round((A146168(n)+A007053(n)-1)/(2^(n-1))*100). %e A146170 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 A146170 Cf. A001358(semiprimes), A007053(Number of primes <= 2^n), A146168(Number of odd squarefree semiprimes < 2^n). %K A146170 nonn %O A146170 1,2 %A A146170 _Washington Bomfim_, Oct 27 2008