OFFSET
1,2
COMMENTS
One less than the associated entry in A153083. - R. J. Mathar, Jan 05 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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