OFFSET
1,4
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
EXAMPLE
The sum of divisors of 4 is 7; its abundancy is 7/4 = 1 + 3/4 so a(4) = 3.
MATHEMATICA
f[n_] := Numerator[FractionalPart[DivisorSigma[1, n]/n]]; Array[f, 81] (* Robert G. Wilson v, Nov 24 2016 *)
PROG
(PARI) a(n) = my(ab = sigma(n)/n); numerator(ab) % denominator(ab);
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Michel Marcus, May 10 2016
STATUS
approved