cp's OEIS Frontend

A153082 Numbers k such that 2*k + 13 is not prime.

%I A153082 #24 Sep 08 2022 08:45:39
%S A153082 1,4,6,7,10,11,13,16,18,19,21,22,25,26,28,31,32,34,36,37,39,40,41,43,
%T A153082 46,49,51,52,53,54,55,56,58,60,61,64,65,66,67,70,71,73,74,76,78,79,81,
%U A153082 82,85,86,87,88,91,94,95,96,97,98,100,101,102,103,104,106,109,111
%N A153082 Numbers k such that 2*k + 13 is not prime.
%C A153082 One less than the associated entry in A153083. - _R. J. Mathar_, Jan 05 2011
%H A153082 Vincenzo Librandi, <a href="/A153082/b153082.txt">Table of n, a(n) for n = 1..1000</a>
%e A153082 Distribution in the following triangular array:
%e A153082 *;
%e A153082 1, 6;
%e A153082 4, 11,18;
%e A153082 7, 16,25,34;
%e A153082 10,21,32,43,54;
%e A153082 13,26,39,52,65,78;
%e A153082 16,31,46,61,76,91,106;
%e A153082 19,36,53,70,87,104,121,138;
%e A153082 22,41,60,79,98,117,136,155,174;
%e A153082 25,46,67,88,109,130,151,172,193,214;
%e A153082 28,51,74,97,120,143,166,189,212,235,258;
%e A153082 31,56,81,106,131,156,181,206,231,256,281,306;
%e A153082 34,61,88,115,142,169,196,223,250,277,304,331,358; etc.
%e A153082 where * marks the negative values of (2*h*k + k + h - 6) with h >= k >= 1. -
%e A153082 _Vincenzo Librandi_, Jan 15 2013
%t A153082 Select[Range[0,100],!PrimeQ[2#+13]&]  (* _Harvey P. Dale_, Mar 17 2011 *)
%o A153082 (Magma) [n: n in [1..120] | not IsPrime(2*n + 13)]; // _Vincenzo Librandi_, Nov 21 2012
%Y A153082 Cf. A153081, A153083, A155550, A153053.
%K A153082 nonn,easy
%O A153082 1,2
%A A153082 _Vincenzo Librandi_, Dec 18 2008