%I #13 Sep 08 2022 08:45:48
%S 5,6,10,13,15,17,18,20,25,27,28,30,31,34,35,36,39,40,41,44,45,48,50,
%T 52,55,57,59,60,61,62,65,69,70,72,74,75,76,80,82,83,85,86,89,90,93,94,
%U 95,96,97,100,103,104,105,109,110,111,112,115,116,118,120,121,122,125,126
%N Numbers n such that 12*n+5 is not prime.
%H Vincenzo Librandi, <a href="/A166563/b166563.txt">Table of n, a(n) for n = 1..1000</a>
%e Distribution of the terms in the following triangular array:
%e *;
%e *,*;
%e *,*,*;
%e *,*,*,*;
%e *,*,6,*,*;
%e *,5,*,*,*,*;
%e *,*,*,*,*,*,*;
%e *,*,*,*,*,18,*,*;
%e *,*,*,*,17,*,*,*,*;
%e *,*,*,*,*,*,*,*,*,*;
%e *,*,13,*,*,*,*,*,36,*,*;
%e *,10,*,*,*,*,*,35,*,*,*,*; etc.
%e where * marks the non-integer values of (2*h*k + k + h - 2)/6 with h >= k >= 1. - _Vincenzo Librandi_, Jan 14 2013
%t Select[Range[0, 200], !PrimeQ[12 # + 5] &] (* _Vincenzo Librandi_, Jan 14 2013 *)
%o (Magma) [n: n in [0..150] | not IsPrime(12*n+5)]; // _Vincenzo Librandi_, Jan 14 2013
%Y Cf. A167055.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Oct 29 2009