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A153082
Numbers k such that 2*k + 13 is not prime.
3
1, 4, 6, 7, 10, 11, 13, 16, 18, 19, 21, 22, 25, 26, 28, 31, 32, 34, 36, 37, 39, 40, 41, 43, 46, 49, 51, 52, 53, 54, 55, 56, 58, 60, 61, 64, 65, 66, 67, 70, 71, 73, 74, 76, 78, 79, 81, 82, 85, 86, 87, 88, 91, 94, 95, 96, 97, 98, 100, 101, 102, 103, 104, 106, 109, 111
OFFSET
1,2
COMMENTS
One less than the associated entry in A153083. - R. J. Mathar, Jan 05 2011
LINKS
EXAMPLE
Distribution in the following triangular array:
*;
1, 6;
4, 11,18;
7, 16,25,34;
10,21,32,43,54;
13,26,39,52,65,78;
16,31,46,61,76,91,106;
19,36,53,70,87,104,121,138;
22,41,60,79,98,117,136,155,174;
25,46,67,88,109,130,151,172,193,214;
28,51,74,97,120,143,166,189,212,235,258;
31,56,81,106,131,156,181,206,231,256,281,306;
34,61,88,115,142,169,196,223,250,277,304,331,358; etc.
where * marks the negative values of (2*h*k + k + h - 6) with h >= k >= 1. -
Vincenzo Librandi, Jan 15 2013
MATHEMATICA
Select[Range[0, 100], !PrimeQ[2#+13]&] (* Harvey P. Dale, Mar 17 2011 *)
PROG
(Magma) [n: n in [1..120] | not IsPrime(2*n + 13)]; // Vincenzo Librandi, Nov 21 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Dec 18 2008
STATUS
approved