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A120227
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Numbers n such that a+n and a*n+1 are prime, case a=5.
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4
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2, 6, 8, 12, 14, 26, 36, 38, 42, 48, 54, 56, 62, 66, 84, 92, 98, 104, 108, 126, 132, 152, 162, 176, 188, 194, 206, 218, 234, 236, 246, 258, 264, 272, 276, 302, 306, 344, 348, 362, 374, 416, 426, 428, 444, 456, 462, 474, 482, 504, 518, 542, 558, 572, 594, 602
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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Reap[Do[Do[If[PrimeQ[{n+x, n*x+1}]=={True, True}, Sow[x]], {x, 2, 1000, 2}], {n, 5, 5}]][[2, 1]]
Select[Range[700], And@@PrimeQ[{#+5, 5#+1}]&] (* Harvey P. Dale, Dec 18 2011 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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