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A120425
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a(n) = maximum value among all k where 1<=k<=n of GCD(k,ceiling(n/k)).
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0
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1, 1, 2, 2, 2, 2, 3, 3, 3, 2, 2, 2, 4, 4, 4, 4, 3, 3, 3, 3, 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 6, 6, 6, 6, 6, 6, 4, 4, 4, 4, 5, 5, 7, 7, 7, 7, 7, 7, 7, 5, 4, 4, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 6, 6, 6, 6, 6, 6, 6, 6, 9, 9, 9, 9, 9, 9, 9, 9, 9, 5, 5, 5, 7, 7, 7, 7, 7, 7, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10
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OFFSET
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1,3
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LINKS
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EXAMPLE
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For n = 10, we have the pairs {k,ceiling(n/k)} of {1,10},{2,5},{3,4},{4,3},{5,2},{6,2},{7,2},{8,2},{9,2},{10,1}. The GCD's of these 10 pairs are 1,1,1,1,1,2,1,2,1,1. Of these, 2 is the largest. So a(10) = 2.
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MATHEMATICA
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Table[Max[Table[GCD[k, Ceiling[n/k]], {k, 1, n}]], {n, 1, 100}] (* Stefan Steinerberger, Jul 22 2006 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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