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A100385
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a(n) is the least number x >= 2 such that for m=x to x+n-1, A006530(m) decreases.
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4
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2, 3, 13, 13, 491, 1851, 12721, 12721, 109453, 586951, 120797465, 624141002, 4044619541, 267793490438, 315400191511, 1285600699441
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OFFSET
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1,1
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COMMENTS
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A006530(m) is the largest prime factor of m.
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LINKS
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FORMULA
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EXAMPLE
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a(5)=491 because the largest prime factors of 491,492,493,494,495 are 491,41,29,19,11.
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MATHEMATICA
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Function[s, Prepend[Reverse@ FoldList[If[#2 > #1, #1, #2] &, Reverse@ #], 2] &@ Map[Function[k, First@ SelectFirst[s, And[Sign@ First@ # == 1, Length@ # == k] &]], Range[Max@ Map[Length, s]]]]@ SplitBy[Flatten[ Partition[Array[{#, FactorInteger[#][[-1, 1]]} &, 10^6], 2, 1] /. {{n_, a_}, {_, b_}} /; n > 0 :> -n Sign[Differences@ {a, b}]], Sign] (* Michael De Vlieger, May 04 2017, Version 10.2 *)
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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