OFFSET
1,2
EXAMPLE
The values of usigma(k)/k are 1, 1.5, 1.8, 1.904..., 1.963..., 1.994...
MATHEMATICA
usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; seq = {}; r = 0; Do[s = usigma[n]/n; If[s < 2 && s > r, AppendTo[seq, n]; r = s], {n, 1, 1000000}]; seq
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Apr 10 2018
STATUS
approved