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A154115
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Numbers n such that n + 3 is prime.
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2
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0, 2, 4, 8, 10, 14, 16, 20, 26, 28, 34, 38, 40, 44, 50, 56, 58, 64, 68, 70, 76, 80, 86, 94, 98, 100, 104, 106, 110, 124, 128, 134, 136, 146, 148, 154, 160, 164, 170, 176, 178, 188, 190, 194, 196, 208, 220, 224, 226, 230, 236, 238, 248, 254, 260, 266, 268, 274, 278
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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a(2) = 2 since (2 + 2)^2 - (2 + 1)^2 - 2 = 5.
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MAPLE
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MATHEMATICA
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a[n_]:=(n+2)^2-(n+1)^2-n; lst={}; Do[If[PrimeQ[a[n]], AppendTo[lst, n]], {n, 6!}]; lst
Select[Range[0, 300], PrimeQ[(#+2)^2-(#+1)^2-#]&] (* Harvey P. Dale, Nov 06 2013 *)
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PROG
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(Magma) [n: n in [0..500] | IsPrime((n+2)^2-(n+1)^2-n)] # Vincenzo Librandi, Nov 26 2010
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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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STATUS
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approved
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