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A112587
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Numbers m such that phi(m) <= 2*tau(m), where phi=A000010 and tau=A000005.
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3
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1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 24, 28, 30, 36, 40, 42, 48, 60, 72, 84, 90, 120
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OFFSET
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1,2
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COMMENTS
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Complement of A112588.
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LINKS
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Table of n, a(n) for n=1..27.
Eric Weisstein's World of Mathematics, Totient Function
Eric Weisstein's World of Mathematics, Divisor Function
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MATHEMATICA
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Select[Range[150], EulerPhi[#]<=2DivisorSigma[0, #]&] (* Harvey P. Dale, Mar 04 2013 *)
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PROG
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(PARI) is(n)=eulerphi(n)<=2*numdiv(n) \\ Charles R Greathouse IV, Feb 21 2013
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CROSSREFS
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Cf. A020488.
Sequence in context: A124455 A072378 A248888 * A141820 A068090 A172121
Adjacent sequences: A112584 A112585 A112586 * A112588 A112589 A112590
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KEYWORD
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nonn,fini,full
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AUTHOR
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Reinhard Zumkeller, Sep 14 2005
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STATUS
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approved
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