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Search: id:A115074
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| A115074 |
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a(n) = largest prime dividing n-th non-squarefree positive integer. |
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3
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| 2, 2, 3, 3, 2, 3, 5, 3, 5, 3, 7, 2, 3, 5, 11, 5, 3, 7, 5, 13, 3, 7, 5, 7, 2, 17, 3, 5, 19, 5, 3, 7, 11, 5, 23, 3, 7, 11, 5, 13, 3, 7, 29, 13, 5, 11, 31, 5, 7, 2, 11, 5, 17, 7, 3, 7, 37, 5, 19, 17, 13, 5, 3, 41, 7, 13, 19, 43, 7, 11, 5, 23, 47, 7, 3, 7, 11, 5, 17, 23, 13, 53, 3, 11, 7, 5, 19, 29, 13
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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A006530(A013929(n))
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EXAMPLE
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12, the 4th non-squarefree positive integer, is 2^2 * 3. 3 is the largest prime dividing 12. So a(4) = 3.
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MAPLE
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with(numtheory): a:=proc(n) if mobius(n)=0 then op(nops(factorset(n)), factorset(n)) fi end: seq(a(n), n=1..270); - Emeric Deutsch (deutsch(AT)duke.poly.edu), Mar 06 2006
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MATHEMATICA
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Needs["NumberTheory`NumberTheoryFunctions`"]; FactorInteger[ # ][[ -1, 1]] & /@ Select[ Range@235, !SquareFreeQ@# &] - Robert G. Wilson v (rgwv(at)rgwv.com), Mar 09 2006
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CROSSREFS
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Cf. A117183, A115090, A013929, A006530.
Sequence in context: A023514 A039645 A048687 this_sequence A039643 A045796 A127684
Adjacent sequences: A115071 A115072 A115073 this_sequence A115075 A115076 A115077
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Mar 01 2006
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu) and Robert G. Wilson v (rgwv(at)rgwv.com), Mar 06 2006
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