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%I #21 Mar 20 2023 12:44:19
%S 5,9,10,15,23,25,29,30,32,40,42,43,44,45,49,58,60,65,70,72,75,80,85,
%T 87,93,94,95,98,99,100,107,109,110,114,117,120,133,135,137,140,155,
%U 158,159,163,164,170,172,175,177,184,185,192,194,197,198,199,204,205
%N Numbers k such that 6*k-5 is composite, but 6*k-1 is prime.
%H Vincenzo Librandi, <a href="/A199718/b199718.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[2, 205], ! PrimeQ[6 # - 5] && PrimeQ[6 # - 1] &] (* _T. N. Noe_, Nov 09 2011 *)
%o (Magma) [ p div 6 +1: n in [4..204] | not IsPrime(p-4) and p mod 6 eq 5 where p is NthPrime(n) ]; // _Bruno Berselli_, Nov 09 2011
%Y Cf. A186243.
%K nonn,easy
%O 1,1
%A _Eleonora Echeverri-Toro_, Nov 09 2011
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