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:
“I have no doubt that it was a principle they fought for, as much as our ancestors, and not to avoid a three-penny tax on their tea; and the results of this battle will be as important and memorable to those whom it concerns as those of the battle of Bunker Hill, at least.”
—Henry David Thoreau (1817–1862)
“The restlessness that comes upon girls upon summer evenings results in lasting trouble unless it is speedily controlled. The right kind of man does not look for a wife on the streets, and the right kind of girl waits till the man comes to her home for her.”
—Sedalia Times (1900)