A153052 - OEIS

%I #23 Sep 08 2022 08:45:39

%S 2,5,8,10,11,14,15,17,20,22,23,25,26,29,30,32,35,36,38,40,41,43,44,45,

%T 47,50,53,55,56,57,58,59,60,62,64,65,68,69,70,71,74,75,77,78,80,82,83,

%U 85,86,89,90,91,92,95,98,99,100,101,102,104,105,106,107,108,110

%N Numbers n such that 2*n + 5 is not a prime.

%C One less than the associated entry in A153238. - _R. J. Mathar_, Jan 05 2011

%C The terms are the values of 2*h*k + k + h - 2, where h and k are positive integers. - _Vincenzo Librandi_, Jan 19 2013

%H Vincenzo Librandi, <a href="/A153052/b153052.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[0, 150], !PrimeQ[2*# + 5] &] (* _Vincenzo Librandi_, Oct 16 2012 *)

%o (Magma) [n: n in [0..110]| not IsPrime(2*n+5)]; // _Vincenzo Librandi_, Oct 16 2012

%Y Cf. A089038, A153238, A154680.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Dec 17 2008