List of repunit primes

A **repunit** is a number consisting entirely of the digit 1. For example, the numbers 1, 11, 111, 1111, and so forth are repunits. The mathematical representation of a repunit \( R_n \) is given by: \[ R_n = \frac{10^n - 1}{9} \] where \( n \) is the number of digits (or "ones") in the repunit.