OFFSET
1,4
COMMENTS
a(n) = 1 for n prime or perfect (A053813).
a(n) > n for n in A069057. - Michel Marcus, May 04 2016
LINKS
Michel Marcus, Table of n, a(n) for n = 1..10000
MATHEMATICA
f[n_] := DivisorSigma[1, n]/n; Table[Numerator[f@ n] - Denominator[f@ n], {n, 76}] (* Michael De Vlieger, Sep 09 2015 *)
PROG
(PARI) a(n) = numerator(ab = sigma(n)/n) - denominator(ab);
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Marcus, Jun 05 2014
STATUS
approved