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%I #15 Sep 08 2022 08:45:39
%S 1,2,3,4,5,7,8,9,10,11,13,14,15,17,18,19,20,21,22,23,25,26,27,29,30,
%T 31,32,33,35,37,38,39,40,41,43,44,45,46,47,48,49,50,51,53,55,56,57,59,
%U 60,61,62,63,65,66,67,68,69,70,71,73,74,75,76,77,79,80,81,83,85,86,87,88
%N Numbers n such that 11*n+5 is not prime.
%H Vincenzo Librandi, <a href="/A153381/b153381.txt">Table of n, a(n) for n = 1..1000</a>
%e Distribution of the even terms in the following triangular array:
%e *;
%e *,*;
%e *,*,4;
%e 2,*,*,*;
%e *,*,*,*,*;
%e *,*,*,*,*,*;
%e *,*,*,*,*,*,20;
%e *,*,*,*,*,*,*,*,;
%e *,*,*,*,*,22,*,*,*;
%e *,*,*,*,*,*,*,32,*,*;
%e *,10,*,*,*,*,*,*,*,*,*;
%e *,*,*,20,*,*,*,*,*,*,*,*;
%e *,*,*,*,*,*,*,*,*,*,56,*,*:
%e *,*,18,*,*,*,*,*,*,*,*,*,*,76;
%e 8,*,*,*,*,*,*,*,*,*,*,70,*,*,*; etc.
%e where * marks the non-integer values of (4*h*k + 2*k + 2*h - 4)/11 with h >= k >= 1. - _Vincenzo Librandi_, Jan 17 2013
%t Select[Range[0, 200], !PrimeQ[11 # + 5] &] (* _Vincenzo Librandi_, Jan 13 2013 *)
%o (Magma) [n: n in [0..150] | not IsPrime(11*n+5)]; // _Vincenzo Librandi_, Jan 13 2013
%Y Cf. A108233.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Dec 25 2008
%E Erroneous comment deleted by _N. J. A. Sloane_, Jun 23 2010
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