OFFSET
1,1
COMMENTS
All entries of A163672 are in the sequence because 2*A163672(n,m)-13 = (2n+1)(2m+1) is not prime. - R. J. Mathar, Jan 05 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
EXAMPLE
Distribution of a(n) > 7 in the following triangular array:
11;
14,19;
17,24,31;
20,29,38,47;
23,34,45,56,67;
26,39,52,65,78,91;
29,44,59,74,89,104,119;
32,49,66,83,100,117,134,151;
35,54,73,92,111,130,149,168,187;
38,59,80,101,122,143,164,185,206,227;
41,64,87,110,133,156,179,202,225,248,271;
44,69,94,119,144,169,194,219,244,269,294,319; etc.
which is obtained by (2*h*k + k + h + 7) with h >= k >= 1. - Vincenzo Librandi, Jan 15 2013
MATHEMATICA
Select[Range[7, 200], !PrimeQ[2 # - 13] &] (* Vincenzo Librandi, Oct 15 2012 *)
PROG
(Magma) [n: n in [7..120] | not IsPrime(2*n - 13)]; // Vincenzo Librandi, Oct 15 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Dec 17 2008
STATUS
approved