# Sierpiński number base 5

A **Sierpiński number base 5** is a value of *k* such that *k × 5 ^{n} + 1* is always composite.

Using the same method presented in the Sierpiński problem article, it was found that *159,986 × 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 159,986 is the smallest Sierpiński number base 5 or not, a distributed computing project was created named Sierpiński-Riesel Base 5