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 A153347 Numbers n>0 such that 7*n-4 is not prime. 1
 2, 4, 6, 7, 8, 10, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 30, 31, 32, 34, 36, 37, 38, 40, 42, 43, 44, 46, 47, 48, 49, 50, 52, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 70, 71, 72, 73, 74, 76, 77, 78, 79, 80, 82, 84, 85, 86, 87, 88, 90, 91, 92 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE Distribution of the odd terms in the following triangular array: *; *,*; *,*,*; *,7,*,*; *,*,*,*,*; *,*,*,*,21,*; 7,*,*,*,*,*,*; *,*,*,*,*,*,37,*; *,*,*,25,*,*,*,*,*; *,*,*,*,*,*,*,*,*,*; *,17,*,*,*,*,*,*,63,*,*; *,*,*,*,*,47,*,*,*,*,*,*; *,*,*,*,43,*,*,*,*,*,*,97,*; 13,*,*,*,*,*,*,71,*,*,*,*,*,*; etc. where * marks the non-integer values of (4*h*k + 2*k + 2*h + 5)/7 with h >= k >= 1. - Vincenzo Librandi, Jan 17 2013 MATHEMATICA Select[Range[1, 200], !PrimeQ[7 # - 4]&] (* Vincenzo Librandi, Jan 13 2013 *) PROG (MAGMA) [n: n in [1..150] | not IsPrime(7*n-4)]; // Vincenzo Librandi, Jan 13 2013 CROSSREFS Cf. A024903. Sequence in context: A138204 A080645 A024413 * A330945 A153167 A227187 Adjacent sequences:  A153344 A153345 A153346 * A153348 A153349 A153350 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Dec 24 2008 EXTENSIONS Erroneous comment deleted by N. J. A. Sloane, Jun 23 2010 STATUS approved

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Last modified April 8 21:44 EDT 2020. Contains 333329 sequences. (Running on oeis4.)