OFFSET
1,2
LINKS
Indranil Ghosh, Table of n, a(n) for n = 1..10000
Mathematical Reflections, Solution to Problem O261, Issue 3, 2013, p. 24.
MATHEMATICA
Select[Range[250], DivisorSigma[1, #]-EulerPhi[#]<=4Sqrt[#]&] (* Harvey P. Dale, Jul 10 2018 *)
PROG
(PARI) isok(n) = sigma(n) - eulerphi(n) <= 4*sqrt(n); \\ Michel Marcus, Jan 06 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Marcus, Jan 06 2017
STATUS
approved