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A064376
Numbers n such that sigma_3(n) > phi(n)^4.
1
2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 36, 40, 42, 48, 54, 60, 66, 70, 72, 78, 84, 90, 102, 114, 120, 126, 132, 150, 168, 180, 210, 330, 420
OFFSET
1,1
COMMENTS
This sequence is finite, since by Grönwall's theorem sigma_3(n) <= sigma(n)^3 << (n log log n)^3 but phi(n)^4 >> (n/log log n)^4. - Charles R Greathouse IV, Nov 19 2015
FORMULA
Solutions to A001158(n) > phi(n)^4.
MATHEMATICA
Select[Range[500], DivisorSigma[3, #]>EulerPhi[#]^4&] (* Harvey P. Dale, Jun 21 2024 *)
PROG
(PARI) is(n)=my(f=factor(n)); sigma(f, 3)>eulerphi(f)^4 \\ Charles R Greathouse IV, Nov 19 2015
CROSSREFS
Sequence in context: A045718 A068005 A055721 * A283808 A068578 A203812
KEYWORD
nonn,fini
AUTHOR
Labos Elemer, Sep 27 2001
STATUS
approved