For n=60,
DivisorSum[60, # &, Mod[#, 5]==4 &]/DivisorSum[60, # &, Mod[#, 5]==1 &] = 4/(1+6) = 4/7
Is it possible to find a number (or all the numbers for instance less than 10^10), for which this ratio (the sum of those divisors which are congruent (-1) mod 5 divided by the sum of those divisors which are congruent (1) mod 5) would equal 1?
