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 A153049 Numbers n such that 2*n - 13 is not a prime. 4
 7, 11, 14, 17, 19, 20, 23, 24, 26, 29, 31, 32, 34, 35, 38, 39, 41, 44, 45, 47, 49, 50, 52, 53, 54, 56, 59, 62, 64, 65, 66, 67, 68, 69, 71, 73, 74, 77, 78, 79, 80, 83, 84, 86, 87, 89, 91, 92, 94, 95, 98, 99, 100, 101, 104, 107, 108, 109, 110, 111, 113, 114, 115, 116 (list; graph; refs; listen; history; text; internal format)
 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 Cf. A097363, A163672. Sequence in context: A338597 A004235 A004236 * A065105 A118797 A080837 Adjacent sequences:  A153046 A153047 A153048 * A153050 A153051 A153052 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Dec 17 2008 STATUS approved

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Last modified January 24 06:43 EST 2021. Contains 340398 sequences. (Running on oeis4.)