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Search: id:A068560
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| A068560 |
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Numbers n such that phi(n)=tau(n)^2. |
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+0
1
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| 1, 5, 34, 63, 76, 128, 136, 170, 315, 364, 380, 444, 640, 680, 972, 1820, 1824, 1836, 2142, 2220, 4788, 4860, 6000, 8064, 8568, 8736, 9120, 9180, 10710, 23940, 40320, 42840, 43680
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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No more terms through 10^9. (Is this sequence finite?) - Ryan Propper (rpropper(AT)stanford.edu), Jun 09 2006
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MATHEMATICA
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Do[If[EulerPhi[n] == DivisorSigma[0, n]^2, Print[n]], {n, 10^9}] - Ryan Propper (rpropper(AT)stanford.edu), Jun 09 2006
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CROSSREFS
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Sequence in context: A140424 A145505 A124936 this_sequence A039773 A135973 A034224
Adjacent sequences: A068557 A068558 A068559 this_sequence A068561 A068562 A068563
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KEYWORD
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easy,more,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 25 2002
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)stanford.edu), Jun 09 2006
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