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%I #16 Sep 08 2022 08:45:39
%S 1,2,4,6,7,8,9,10,12,13,14,16,17,18,19,20,22,24,25,26,28,29,30,31,32,
%T 34,35,36,37,38,39,40,41,42,43,44,46,48,49,50,52,54,55,56,58,59,60,61,
%U 62,64,66,67,68,69,70,72,73,74,75,76,78,79,80,82,83,84,85,86,87,88,89,90
%N Numbers n such that 7*n+2 is not prime.
%H Vincenzo Librandi, <a href="/A153351/b153351.txt">Table of n, a(n) for n = 1..1000</a>
%e Distribution of the odd terms in the following triangular array:
%e 1;
%e *,*;
%e *,*,*;
%e *,*,*,*;
%e *,*,*,*,17;
%e *,9,*,*,*,*;
%e *,*,*,19,*,*,*;
%e 7,*,*,*,*,*,*,41;
%e *,*,*,*,*,35,*,*,*;
%e *,*,*,*,*,*,*,*,*,*;
%e *,*,*,*,*,*,49,*,*,*,*;
%e *,*,*,*,39,*,*,*,*,*,*,89;
%e *,19,*,*,*,*,*,*,73,*,*,*,*; etc.
%e where * marks the non-integer values of (4*h*k + 2*k + 2*h - 1)/7 with h >= k >= 1. - _Vincenzo Librandi_, Jan 17 2013
%t Select[Range[200], !PrimeQ[7 # + 2] &] (* _Vincenzo Librandi_, Jan 13 2013 *)
%o (Magma) [n: n in [0..150] | not IsPrime(7*n + 2)]; // _Vincenzo Librandi_, Jan 13 2013
%Y Cf. A105772.
%K nonn,easy
%O 1,2
%A _Vincenzo Librandi_, Dec 24 2008
%E Erroneous comment deleted by _N. J. A. Sloane_, Jun 23 2010
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