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A153238
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Numbers n such that 2n + 3 is composite.
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16
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3, 6, 9, 11, 12, 15, 16, 18, 21, 23, 24, 26, 27, 30, 31, 33, 36, 37, 39, 41, 42, 44, 45, 46, 48, 51, 54, 56, 57, 58, 59, 60, 61, 63, 65, 66, 69, 70, 71, 72, 75, 76, 78, 79, 81, 83, 84, 86, 87, 90, 91, 92, 93, 96, 99, 100, 101, 102, 103, 105, 106, 107, 108, 109, 111, 114
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| One less than the associated value in A047845. - R. J. Mathar, Jan 05 2011
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FORMULA
| a(n) ~ n.
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MATHEMATICA
| lst={}; Do[If[ !PrimeQ[2*n+3], AppendTo[lst, n]], {n, 6!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Jan 10 2009]
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PROG
| (PARI) for(n=1, 115, if(!isprime(2*n+3), print1(n, ", ")))
(MAGMA) [ n: n in [0..120] | not IsPrime(2*n+3) ];
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CROSSREFS
| Cf. A067076.
Sequence in context: A024795 A000408 A025321 * A201462 A189302 A086883
Adjacent sequences: A153235 A153236 A153237 * A153239 A153240 A153241
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KEYWORD
| nonn,easy
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AUTHOR
| Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Dec 21 2008
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EXTENSIONS
| Edited by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 07 2009
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