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Search: id:A067385
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| A067385 |
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a(n) is smallest x such that sigma(phi(x))/sigma(x) = n. |
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+0
6
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OFFSET
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1,2
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MATHEMATICA
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a[ n_ ] := For[ x=1, True, x++, If[ DivisorSigma[ 1, EulerPhi[ x ] ]/DivisorSigma[ 1, x ]==n, Return[ x ] ] ]
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CROSSREFS
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Cf. A033631, A066831, A067382, A067383, A067384.
Sequence in context: A001570 A020544 A009015 this_sequence A097260 A091540 A057799
Adjacent sequences: A067382 A067383 A067384 this_sequence A067386 A067387 A067388
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KEYWORD
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more,nonn
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AUTHOR
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Dean Hickerson (dean(AT)math.ucdavis.edu), Jan 20 2002
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EXTENSIONS
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a(5) from Vim Wenders (vim(AT)gmx.li), Mar 11 2007
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