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%I #18 Sep 08 2022 08:45:39
%S 3,7,8,13,14,18,19,21,23,27,28,30,33,35,38,40,41,42,43,47,48,49,52,53,
%T 56,58,59,63,64,66,68,70,73,74,77,78,79,81,83,84,85,87,88,91,92,93
%N Numbers n such that 6*n + 7 is not prime.
%C One less than the associated entry in A046954. - _R. J. Mathar_, Jan 05 2011
%H Vincenzo Librandi, <a href="/A153219/b153219.txt">Table of n, a(n) for n = 1..1000</a>
%e Distribution of the terms in the following triangular array:
%e *;
%e *,3;
%e *,*,7;
%e *,*,*,*;
%e *,8,*,*,19;
%e *,*,14,*,*,27;
%e *,*, *,*,*, *,*;
%e *,13,*,*,30,*,*,47;
%e *,*,21,*,*,40,*,*,59;
%e *,*,*, *,*, *,*,*, *,*;
%e *,18,*,*,41,*,*,64,*,*,87;
%e *,*,28,*,*,53,*,*,78,*,*,103; etc.
%e where * marks the non-integer values of (2*h*K + k + h - 3)/3 with h >= k >= 1. - _Vincenzo Librandi_, Jan 15 2013
%t Select[Range[0, 200], !PrimeQ[6 # + 7] &] (* _Vincenzo Librandi_, Jan 12 2013 *)
%o (Magma) [n: n in [0..110] | not IsPrime(6*n+7)]; // _Vincenzo Librandi_, Jan 12 2013
%Y Cf. A153218.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Dec 21 2008
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