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%I #7 Nov 21 2013 12:50:01
%S 1,3,10,33,43,49,50,57,63,100,113,120,131,140,149,159,173,195,206,224,
%T 230,277,284,303,315,320,332,366,373,394,395,401,448,463,469,471,473,
%U 477,483,484,492,513,524,530,534,537,543,555,558,576,577,592,600,608
%N Numbers n such that 2*prime(n) and 2*prime(n+1) are consecutive semiprimes.
%C There are no semiprimes strictly between 2*prime(n) and 2*prime(n+1).
%C A174956(A100484(a(n+1)))=A174956(A100484(a(n)))+1. [From _Reinhard Zumkeller_, Apr 03 2010]
%F A000040(a(n)) = A001358(A174797(n))/2.
%e a(1)=1 because 2*prime(1)=4=semiprime(1) and 2*prime(1+1)=6=semiprime(2).
%e a(2)=3 because 2*prime(3)=10=semiprime(4) and 2*prime(3+1)=14=semiprime(5).
%t PrimePi[First[#]]&/@Select[Partition[Select[Range[20000],PrimeOmega[#] == 2&], 2,1]/2,And@@IntegerQ/@#&] (* _Harvey P. Dale_, Nov 19 2011 *)
%Y Cf. A000040, A001358, A174797.
%K nonn
%O 1,2
%A _Juri-Stepan Gerasimov_, Mar 29 2010
%E Edited, corrected and extended by _Ray Chandler_, Apr 07 2010
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