On Divisibility by Nine of the Sums of Even Amicable Pairs
Elvin Lee · Mathematics of Computation · 1969
Most known even amicable pairs have sums divisible by nine [9]. The general form of the exceptions to the rule of divisibility by nine (Gardner’s rule) is deduced and the results expressed in the form of a theorem. A computer search based on a corollary to the theorem is described and six new exceptions to Gardner’s rule are found.