1,1

This sequence is finite, since by GrĂ¶nwall'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

Table of n, a(n) for n=1..38.

Solutions to A001158(n) > phi(n)^4.

(PARI) is(n)=my(f=factor(n)); sigma(f, 3)>eulerphi(f)^4 \\ Charles R Greathouse IV, Nov 19 2015

Cf. A001158, A000010.

Sequence in context: A045718 A068005 A055721 * A283808 A068578 A203812

Adjacent sequences: A064373 A064374 A064375 * A064377 A064378 A064379

nonn,fini

Labos Elemer, Sep 27 2001

approved