Other Results
In every known case, the numbers of a pair are either both even or both odd. It is not known whether an even-odd pair of amicable numbers exists, but if it does, the even number must either be a square number or twice one, and the odd number must be a square number. Also, every known pair shares at least one common factor, higher than 1. It is not known whether a pair of coprime amicable numbers exists, though if any does, the product of the two must be greater than 1067. Also, a pair of coprime amicable numbers cannot be generated by Thabit's formula (above), nor by any similar formula.
In 1955, Paul Erdős showed that the density of amicable numbers, relative to the positive integers, was 0.
Read more about this topic: Amicable Numbers
Famous quotes containing the word results:
““The ideal reasoner,” he remarked, “would, when he had once been shown a single fact in all its bearings, deduce from it not only all the chain of events which led up to it but also all the results which would follow from it.””
—Sir Arthur Conan Doyle (1859–1930)
“Being a parent is unlike any previous job—the results of any one action are not clearly visible for a long time, if at all.”
—Anonymous Mother. As quoted in Between Generations by Ellen Galinsky, ch. 2 (1981)