OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
MATHEMATICA
For[ n=1, True, n++, If[ DivisorSigma[ 1, EulerPhi[ n ] ]/DivisorSigma[ 1, n ]==3, Print[ n ] ] ]
Select[Range[250000], DivisorSigma[1, EulerPhi[#]]/DivisorSigma[1, #]==3&] (* Harvey P. Dale, Sep 08 2024 *)
PROG
(PARI) is(n)=sigma(eulerphi(n=factor(n)))/sigma(n)==3 \\ Charles R Greathouse IV, Nov 27 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Dean Hickerson, Jan 20 2002
STATUS
approved