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A154611
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Numbers n such that 7*n+3 is not prime.
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1
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1, 3, 5, 6, 7, 9, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27, 29, 30, 31, 33, 35, 36, 37, 39, 41, 42, 43, 45, 46, 47, 48, 49, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79
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OFFSET
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1,2
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COMMENTS
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The even terms are the integer values of (4*h*k + 2*k + 2*h - 2)/7, where h and k are positive integers. - Vincenzo Librandi, Jan 17 2013
The corresponding composite numbers are 10, 24, 38, 45, 52, 66, 80, 87, 94, 108, 115, 122, 129, ... - Michael B. Porter, Jan 17 2013
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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MATHEMATICA
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With[{nn=100}, Sort[Join[Range[1, nn-1, 2], Select[Range[0, nn, 2], !PrimeQ[ 7#+3]&]]]] (* Harvey P. Dale, Aug 22 2012 *)
Select[Range[0, 100], !PrimeQ[7 # + 3]&] (* Vincenzo Librandi, Apr 05 2013 *)
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PROG
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(MAGMA) [n: n in [0..80] | not IsPrime(7*n+3)]; // Vincenzo Librandi, Apr 05 2013
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CROSSREFS
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Cf. A089033, A045437, A017017.
Sequence in context: A103826 A079905 A321321 * A189669 A164028 A301729
Adjacent sequences: A154608 A154609 A154610 * A154612 A154613 A154614
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KEYWORD
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nonn,easy
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AUTHOR
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Vincenzo Librandi, Jan 15 2009
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EXTENSIONS
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Erroneous comments deleted by N. J. A. Sloane, Jun 23 2010
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STATUS
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approved
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