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A153245 Numbers n>1 such that 6*n-7 is not prime.

%I A153245 #22 Sep 08 2022 08:45:39
%S A153245 7,12,14,17,21,22,25,27,28,32,35,36,37,38,42,47,49,51,52,55,56,57,58,
%T A153245 62,63,64,67,69,70,72,74,77,80,82,84,87,89,90,91,92,93,97,98,102,103,
%U A153245 105,106,107,112,113,116,117,119,120,122,123,124,126,127,129,131,132,133
%N A153245 Numbers n>1 such that 6*n-7 is not prime.
%C A153245 One more than the associated value in A046953. - _R. J. Mathar_, Jan 05 2011
%H A153245 Vincenzo Librandi, <a href="/A153245/b153245.txt">Table of n, a(n) for n = 1..1000</a>
%e A153245 Distribution of the terms in the following triangular array:
%e A153245 *;
%e A153245 *,*;
%e A153245 *,7,*;
%e A153245 *,*,*,*;
%e A153245 *,*,14,*,*;
%e A153245 *,12,*,*,25,*;
%e A153245 *, *,*,*,*, *,*;
%e A153245 *,*,21,*,*,38,*,*;
%e A153245 *,17,*,*,36,*,*,55,*;
%e A153245 *,*, *,*,*, *,*,*, *,*;
%e A153245 *,*,28,*,*,51,*,*,74,*,*;
%e A153245 *,22,*,*,47,*,*,72,*,*,97,*; etc.
%e A153245 where * marks the non-integer values of (2*h*k + k + h + 4)/3 with h >= k >= 1. - _Vincenzo Librandi_, Jan 17 2013
%t A153245 Select[Range[2, 200], !PrimeQ[6 # - 7] &] (* _Vincenzo Librandi_, Jan 12 2013 *)
%o A153245 (Magma) [n: n in [2..150] | not IsPrime(6*n - 7)]; // _Vincenzo Librandi_, Jan 12 2013
%Y A153245 Cf. A046953, A153134, A153135.
%K A153245 nonn,easy
%O A153245 1,1
%A A153245 _Vincenzo Librandi_, Dec 21 2008
%E A153245 More terms from _Vladimir Joseph Stephan Orlovsky_, Dec 23 2008