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A046954
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Numbers k such that 6*k + 1 is nonprime.
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11
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0, 4, 8, 9, 14, 15, 19, 20, 22, 24, 28, 29, 31, 34, 36, 39, 41, 42, 43, 44, 48, 49, 50, 53, 54, 57, 59, 60, 64, 65, 67, 69, 71, 74, 75, 78, 79, 80, 82, 84, 85, 86, 88, 89, 92, 93, 94, 97, 98, 99, 104, 106, 108, 109, 111, 113, 114, 116, 117, 119, 120, 124, 127, 129, 130, 132, 133, 134, 136, 139, 140
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OFFSET
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1,2
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COMMENTS
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These numbers (except 0) can be written as 6xy +-(x+y) for x > 0, y > 0. - Ron R Spencer, Aug 01 2016
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LINKS
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EXAMPLE
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a(2)=8 because 6*8 + 1 = 49, which is composite.
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MAPLE
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remove(k-> isprime(6*k+1), [$0..140])[]; # Muniru A Asiru, Feb 22 2019
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MATHEMATICA
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a = Flatten[Table[If[PrimeQ[6*n + 1] == False, n, {}], {n, 0, 50}]] (* Roger L. Bagula, May 17 2007 *)
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PROG
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(Haskell)
a046954 n = a046954_list !! (n-1)
a046954_list = map (`div` 6) $ filter ((== 0) . a010051' . (+ 1)) [0, 6..]
(Magma) [n: n in [0..250] | not IsPrime(6*n+1)]; // G. C. Greubel, Feb 21 2019
(Sage) [n for n in (0..250) if not is_prime(6*n+1)] # G. C. Greubel, Feb 21 2019
(GAP) Filtered([0..250], k-> not IsPrime(6*k+1)) # G. C. Greubel, Feb 21 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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