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A053671
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Least number coprime to n, n+1 and n+2.
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7
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5, 5, 7, 7, 11, 5, 5, 7, 7, 7, 5, 5, 11, 11, 7, 5, 5, 7, 11, 13, 5, 5, 7, 7, 7, 5, 5, 11, 7, 7, 5, 5, 13, 11, 11, 5, 5, 7, 7, 11, 5, 5, 7, 7, 7, 5, 5, 11, 11, 7, 5, 5, 7, 13, 13, 5, 5, 7, 7, 7, 5, 5, 11, 7, 7, 5, 5, 11, 11, 11, 5, 5, 7, 7, 13, 5, 5, 7, 7, 7, 5, 5, 11, 11, 7, 5, 5, 7, 11, 11, 5, 5
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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a[n_] := (k = 5; While[! (CoprimeQ[k, n] && CoprimeQ[k, n+1] && CoprimeQ[k, n+2]), k++]; k); Table[a[n], {n, 1, 92}] (* Jean-François Alcover, Nov 30 2011 *)
lnc[n_]:=Module[{k=5, c=n+{0, 1, 2}}, While[!And@@CoprimeQ[k, c], k=k+2]; k]; Array[lnc, 100] (* Harvey P. Dale, Mar 01 2015 *)
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PROG
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(Haskell)
a053671 n = f $ drop 2 a000040_list where
f (p:ps) | (n `mod` p) * ((n+1) `mod` p) * ((n+2) `mod` p) > 0 = p
| otherwise = f ps
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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