Definition:Repunit

Definition
Let $b \in \Z_{>1}$ be an integer greater than $1$.

Let a (positive) integer $n$, greater than $b$ be expressed in base $b$.

$n$ is a repunit base $b$ $n$ is a repdigit number base $b$ whose digits are $1$.

That is, $n$ is a repunit base $b$ all of the digits of $n$ are $1$.

When $b$ is the usual base $10$, $n$ is merely referred to as a repunit.