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A156899
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a(n) = the largest prime power <= the n-th positive squarefree integer.
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4
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1, 2, 3, 5, 5, 7, 9, 11, 13, 13, 13, 17, 19, 19, 19, 23, 25, 29, 29, 31, 32, 32, 32, 37, 37, 37, 41, 41, 43, 43, 47, 49, 53, 53, 53, 53, 59, 61, 61, 64, 64, 67, 67, 67, 71, 73, 73, 73, 73, 79, 81, 83, 83, 83, 83, 89, 89, 89, 89, 89, 97, 101, 101, 103, 103, 103, 107, 109, 109
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OFFSET
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1,2
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COMMENTS
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The first positive squarefree integer is considered to be 1 here.
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LINKS
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MATHEMATICA
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Block[{nn = 110, s}, s = Select[Range[nn], SquareFreeQ]; Map[If[# == 1, 1, SelectFirst[# - Range[0, # - 1], PrimePowerQ]] &, s]] (* Michael De Vlieger, Oct 30 2017 *)
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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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