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%I #20 Sep 08 2022 08:45:23
%S 25,49,55,85,91,115,121,133,145,169,187,205,217,235,247,253,259,265,
%T 289,295,301,319,355,361,391,403,415,427,445,451,469,481,493,505,511,
%U 517,529,535,553,559,565,583,589,649,655,667,679,685,697,703,721,745
%N Semiprimes of the form 6n + 1.
%C Union of A108164 and A108166.
%C Subsequence of A091300. - _Zak Seidov_, Dec 28 2015
%H Vincenzo Librandi, <a href="/A112771/b112771.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = 6 * A112775(n) +1.
%t Select[6 Range[0, 200] + 1, PrimeOmega[#] == 2&] (* _Vincenzo Librandi_, Sep 22 2012 *)
%o (Magma) IsSemiprime:=func<n | &+[d[2]: d in Factorization(n)] eq 2>; [s: n in [2..150] | IsSemiprime(s) where s is 6*n + 1]; // _Vincenzo Librandi_, Sep 22 2012
%K easy,nonn
%O 1,1
%A _Jonathan Vos Post_ and _Ray Chandler_, Oct 15 2005
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