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A153129 Numbers n such that 8*n + 5 is not prime. 1

%I #15 Sep 08 2022 08:45:39

%S 2,5,8,9,10,11,14,15,16,17,20,23,25,26,27,29,30,31,32,35,37,38,40,41,

%T 42,44,45,47,50,51,53,54,55,56,58,59,60,61,62,64,65,66,68,70,71,72,73,

%U 74,75,77,78,79,80,83,85,86,89,90,92,93,95,97,98,100

%N Numbers n such that 8*n + 5 is not prime.

%H Vincenzo Librandi, <a href="/A153129/b153129.txt">Table of n, a(n) for n = 1..1000</a>

%e *;

%e *, *;

%e 2, *, *;

%e *, 5, *, *;

%e *, *, 9, *, *;

%e *, *, *, 14, *, *;

%e 5, *, *, *, 20, *, *;

%e *, 10, *, *, *, 27, *, *;

%e *, *, 16, *, *, *, 35, *, *;

%e where * marks the non-integer values of (2*n*k + k + n - 2)/4 with n >= k >= 1. - _Vincenzo Librandi_, Nov 30 2012

%t Select[Range[200], !PrimeQ[8# + 5] &] (* _Vincenzo Librandi_, Nov 30 2012 *)

%o (Magma) [n: n in [1..120] | not IsPrime(8*n + 5)]; // _Vincenzo Librandi_, Nov 30 2012

%Y Cf. A105133.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Dec 19 2008

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Last modified March 29 01:36 EDT 2024. Contains 371264 sequences. (Running on oeis4.)