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A117183
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a(n) = smallest prime dividing n-th nonsquarefree positive integer.
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3
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2, 2, 3, 2, 2, 2, 2, 2, 5, 3, 2, 2, 2, 2, 2, 3, 2, 7, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 11, 2, 5, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 13, 3, 2, 5, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 3, 2, 5, 2, 2, 2, 2, 2, 3, 2, 2, 2
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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12, the 4th nonsquarefree positive integer, is 2^2 * 3. 2 is the smallest prime dividing 12. So a(4) = 2.
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MAPLE
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with(numtheory): a:=proc(n) if mobius(n)=0 then op(1, factorset(n)) fi end: seq(a(n), n=1..345); # Emeric Deutsch
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MATHEMATICA
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Needs["NumberTheory`NumberTheoryFunctions`"]; FactorInteger[ # ][[1, 1]] & /@ Select[ Range@252, !SquareFreeQ@# &] (* Robert G. Wilson v *)
FactorInteger[#][[1, 1]]&/@DeleteCases[Range[300], _?SquareFreeQ] (* Harvey P. Dale, Jun 02 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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