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A051698
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Closest prime to n that is different from n (break ties by taking the smaller prime).
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3
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2, 2, 3, 2, 3, 3, 5, 5, 7, 7, 11, 13, 11, 11, 13, 13, 17, 19, 17, 17, 19, 19, 23, 19, 23, 23, 23, 29, 29, 31, 29, 29, 31, 31, 31, 37, 37, 41, 37, 37, 41, 43, 41, 41, 43, 43, 47, 43, 47, 47, 47, 53, 53, 47, 53, 53, 53, 59, 59, 61, 59, 59, 61, 61, 61, 67, 67, 71, 67, 67, 71, 73
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OFFSET
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0,1
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LINKS
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EXAMPLE
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Closest primes to 0,1,2,3,4 are 2,2,3,2,3.
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MATHEMATICA
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cp[n_]:=Module[{p1=NextPrime[n, -1], p2=NextPrime[n]}, If[p2-n<n-p1, p2, p1]]; Join[{2}, Table[cp[k], {k, 80}]] (* Harvey P. Dale, Dec 11 2018 *)
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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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