%I A125527
%S A125527 0,1,2,6,10,22,42,82,157,304,589,1124,2186,4192,8110,15658,30253,58546,
%T A125527 113307,219759,426180,827702,1608668,3129211,6091437,11868599,23140878,
%U A125527 45150717,88157689,172235073,336717854,658662065,1289149627,2524532330
%N A125527 Number of semiprimes <= 2^n.
%H A125527 Robert G. Wilson v, <a href="b125527.txt">Table of n, a(n) for n = 1..49</
               a> [File corrected Mar 12 2007]
%H A125527 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Semiprime.html">Link to a section of The World of Mathematics</a>
               .
%t A125527 SemiPrimePi[n_] := Sum[ PrimePi[ n/Prime@i] - i + 1, {i, PrimePi@ Sqrt@n}]; 
               Table[ SemiPrimePi[2^n], {n, 47}]
%Y A125527 Cf. A126279, A066265, A007053, A127396.
%Y A125527 Sequence in context: A001172 A167512 A055895 this_sequence A049750 A134016 
               A072297
%Y A125527 Adjacent sequences: A125524 A125525 A125526 this_sequence A125528 A125529 
               A125530
%K A125527 nonn
%O A125527 1,3
%A A125527 Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 29 2006