%I A064911
%S A064911 0,0,0,1,0,1,0,0,1,1,0,0,0,1,1,0,0,0,0,0,1,1,0,0,1,1,0,0,0,0,0,0,1,1,1,
%T A064911 0,0,1,1,0,0,0,0,0,0,1,0,0,1,0,1,0,0,0,1,0,1,1,0,0,0,1,0,0,1,0,0,0,1,0,
%U A064911 0,0,0,1,0,0,1,0,0,0,0,1,0,0,1,1,1,0,0,0,1,0,1,1,1,0,0,0,0,0,0,0,0,0,0
%N A064911 If n semiprime (or 2-almost primes) than 1 else 0.
%C A064911 a(A100959(n)) = 0 and a(A001358(n)) = 1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), 
               Nov 24 2004
%H A064911 <a href="Sindx_Ch.html#char_fns">Index entries for characteristic functions</
               a>
%H A064911 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Semiprime.html">Semiprime</a>
%H A064911 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               PrimeZetaFunction.html">Prime zeta function primezeta(s)</a>.
%F A064911 Dirichlet g.f. (primezeta(2s) + primezeta(s)^2)/2. - Frank Adams-Watters 
               (FrankTAW(AT)Netscape.net), Jun 09 2006
%Y A064911 Cf. A064899-A064910, A053409, A046413.
%Y A064911 Sequence in context: A102215 A038189 A072783 this_sequence A099618 A106002 
               A066247
%Y A064911 Adjacent sequences: A064908 A064909 A064910 this_sequence A064912 A064913 
               A064914
%K A064911 nonn
%O A064911 1,1
%A A064911 Patrick De Geest (pdg(AT)worldofnumbers.com), Oct 13 2001.