A068578 - OEIS

A068578

Numbers k such that tau(k)*sigma(k) > k*phi(k).

2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24, 30, 36, 40, 42, 48, 60, 72, 84, 90, 120, 180

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OFFSET

1,1

COMMENTS

Numbers k such that A064840(k) > A002618(k).

LINKS

MATHEMATICA

Select[Range[180], DivisorSigma[0, #] * DivisorSigma[1, #] > # * EulerPhi[#] &] (* Amiram Eldar, Jun 12 2022 *)

PROG

(PARI) is(k) = {my(f=factor(k)); numdiv(k)*sigma(k) > k*eulerphi(k); } \\ Jinyuan Wang, Apr 05 2020

CROSSREFS

KEYWORD

nonn,easy,fini,full

AUTHOR

STATUS

approved