OFFSET
1,2
COMMENTS
Sum_{d|n} (pod(d)/tau(d)) > 1 for all n > 1.
EXAMPLE
For n=4; Sum_{d|4} (pod(d)/sigma(d)) = pod(1)/sigma(1) + pod(2)/sigma(2) + pod(4)/sigma(4) = 1/1 + 2/3 + 8/7 = 59/21; a(4) = 21.
MATHEMATICA
Array[Denominator@ DivisorSum[#, Apply[Times, Divisors@ #]/DivisorSigma[1, #] &] &, 60] (* Michael De Vlieger, Mar 24 2019 *)
PROG
(Magma) [Denominator(&+[&*[c: c in Divisors(d)] / SumOfDivisors(d): d in Divisors(n)]): n in [1..100]]
(PARI) a(n) = denominator(sumdiv(n, d, vecprod(divisors(d))/sigma(d))); \\ Michel Marcus, Mar 23 2019
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Jaroslav Krizek, Mar 22 2019
STATUS
approved