cp's OEIS Frontend

A153086 Numbers n such that 4*n+7 is not prime.

%I A153086 #18 Jul 22 2025 06:16:26
%S A153086 2,5,7,8,11,12,14,17,20,21,22,23,26,27,28,29,32,34,35,37,38,41,42,44,
%T A153086 45,47,49,50,52,53,56,57,59,60,62,63,65,67,68,70,71,72,73,74,77,78,79,
%U A153086 80,82,83,84,86,87,89,91,92,95,96,97,98,99,100,101,102,104,105,107
%N A153086 Numbers n such that 4*n+7 is not prime.
%H A153086 Vincenzo Librandi, <a href="/A153086/b153086.txt">Table of n, a(n) for n = 1..1000</a>
%e A153086 *;
%e A153086 2, *;
%e A153086 *, 7, *;
%e A153086 5, *, 14, *;
%e A153086 *, 12, *, 23, *;
%e A153086 8, *, 21, *, 34, *;
%e A153086 *, 17, *, 32, *, 47, *; etc.
%e A153086 where * marks the non-integer values of (2*n*k + k + n - 3)/2 with n >= k >= 1. - _Vincenzo Librandi_, Nov 21 2012
%t A153086 Select[Range[200], !PrimeQ[4# + 7] &] (* _Vincenzo Librandi_, Nov 21 2012 *)
%o A153086 (Magma) [n: n in [1..120] | not IsPrime(4*n + 7)]; // _Vincenzo Librandi_, Nov 21 2012
%Y A153086 Cf. A089986, A153053.
%K A153086 nonn,easy
%O A153086 1,1
%A A153086 _Vincenzo Librandi_, Dec 18 2008