Currently there may be errors shown on top of a page, because of a missing Wiki update (PHP version and extension DPL3). |

**Navigation**

Topics | Help • Register • News • History • How to • Sequences statistics • Template prototypes |

# Riesel number base 5

A **Riesel number base 5** is a value of *k* such that `k`•5^{n}-1 is always a composite number.

Using the same method presented in the Riesel problem article, it was found that 346802•5^{n}-1 is multiple of 3, 7, 13, 31 or 601 (the covering set) depending on the value of n, so it is always composite.

In order to demonstrate whether 346,802 is the smallest Riesel number base 5 or not, a distributed computing project was created named Sierpiński-Riesel Base 5.