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## Homework Statement

A base b repunit is an integer with base b expansion containing all 1's.

a) Determine which base b repunits are divisible by factors b-1

b) Determine which base b repunits are divisible by factors b+1

## Homework Equations

[tex]R_{n}=\frac{b^{n}-1}{b-1}[/tex]

## The Attempt at a Solution

So a repunit of base 3 would be n=2 since we get 1. I don't get how to find any beyond this point though. I tried using other n numbers but I didn't get any others that come out to all 1's.