OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
EXAMPLE
For n = 4; a(4) = numerator((Sum_{d|4} sigma(d)) / sigma(4)) = numerator((1 + 3 + 7) / (1 + 2 + 4)) = numerator(11/7) = 11.
MATHEMATICA
Table[Numerator[Sum[DivisorSigma[1, d], {d, Divisors[n]}] / DivisorSigma[1, n]], {n, 1, 100}] (* Vaclav Kotesovec, Dec 22 2018 *)
PROG
(Magma) [Numerator(&+[SumOfDivisors(d): d in Divisors(n)] / SumOfDivisors(n)): n in [1..1000]]
(PARI) a(n) = numerator(sumdiv(n, d, sigma(d))/sigma(n)); \\ Michel Marcus, Dec 22 2018
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Jaroslav Krizek, Dec 22 2018
STATUS
approved