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%I #32 Jul 31 2021 19:18:32
%S 15,35,77,91,143,187,209,221,247,299,323,391,437,493,527,551,589,667,
%T 703,713,851,899,943,989,1073,1147,1189,1247,1271,1333,1363,1457,1517,
%U 1537,1591,1643,1739,1763,1829,1891,1927,1961,2021,2173,2183,2257,2279
%N Odd semiprimes pq with p < q < 2p.
%C Numbers k such that A082647(k) = A000005(k) - 1 = 3.
%C A082647(p^2) = A000005(p^2) - 1 = 2, where p is odd prime.
%C Numbers n such that A229964(n) = 2. - _Eric M. Schmidt_, Oct 05 2013
%H Amiram Eldar, <a href="/A082663/b082663.txt">Table of n, a(n) for n = 1..10000</a> (terms 1...1000 from Vincenzo Librandi)
%t f[n_]:=Last/@FactorInteger[n]=={1,1}&&FactorInteger[n][[1,1]]>2&&Floor[FactorInteger[n][[2,1]]/FactorInteger[n][[1,1]]]==1;lst={};Do[If[f[n],AppendTo[lst,n]],{n,7!}];lst (* _Vladimir Joseph Stephan Orlovsky_, May 19 2010 *)
%t pq2pQ[n_]:=Module[{fi=FactorInteger[n][[All,1]]},PrimeOmega[n]==2 && fi[[1]]< fi[[2]]< 2fi[[1]]]; Select[Range[1,2301,2],pq2pQ]//Quiet (* _Harvey P. Dale_, Jul 31 2021 *)
%o (PARI) list(lim)=my(v=List()); forprime(p=3, sqrtint(lim\=1), forprime(q=p+1,min(lim\p,2*p), listput(v,p*q))); Set(v) \\ _Charles R Greathouse IV_, Mar 03 2021
%Y Cf. A000005, A056913, A046388, A082647, A229964.
%K easy,nonn
%O 1,1
%A _Naohiro Nomoto_, May 18 2003
%E New name based on a Jan 23 2004 comment from _Vladeta Jovovic_ - _Charles R Greathouse IV_, Mar 03 2021
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