OFFSET
1,2
COMMENTS
Abundance-radius = abs(sigma(n)-2n) does not exceed square root.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
abu[x_] := Abs[DivisorSigma[1, x]-2*x] Do[If[ !Greater[abu[n], Sqrt[n]//N], Print[n]], {n, 1, 100000}]
PROG
(PARI) is(n)=abs(sigma(n)-2*n)<=sqrtint(n) \\ Charles R Greathouse IV, Mar 09 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 20 2003
EXTENSIONS
New name from Charles R Greathouse IV, Mar 09 2014
STATUS
approved