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A168063
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Numbers k such that exactly two of {k-2, k-1, k+1, k+2} are primes.
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2
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1, 3, 5, 6, 9, 12, 15, 18, 21, 30, 39, 42, 45, 60, 69, 72, 81, 99, 102, 105, 108, 111, 129, 138, 150, 165, 180, 192, 195, 198, 225, 228, 231, 240, 270, 279, 282, 309, 312, 315, 348, 351, 381, 399, 420, 432, 441, 459, 462, 465, 489, 501, 522, 570, 600, 615, 618
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OFFSET
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1,2
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COMMENTS
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LINKS
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MATHEMATICA
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Select[Range[700], Count[#+{-2, -1, 1, 2}, _?PrimeQ]==2&] (* Harvey P. Dale, Jan 24 2014 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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Corrected (105 inserted, 609 removed) by R. J. Mathar, Jun 04 2010
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STATUS
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approved
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