The divisibility of a^n-b^n by powers of n
Number Theory
2009-09-15 v1
Abstract
For given integers a,b, and j at least 1 we determine the set of integers n for which a^n-b^n is divisible by n^j. For j=1,2, this set is usually infinite; we find explicitly the exceptional cases for which a,b the set is finite. For j=2, we use Zsigmondy's Theorem for this. For j at least 3 and gcd(a,b)=1, the set is probably always finite; this seems difficult to prove, however. We also show that determination of the set of integers n for which a^n+b^n is divisible by n^j can be reduced to that of the above set.
Keywords
Cite
@article{arxiv.0909.2598,
title = {The divisibility of a^n-b^n by powers of n},
author = {Chris Smyth},
journal= {arXiv preprint arXiv:0909.2598},
year = {2009}
}