Riesel number

This article defines a property that can be evaluated for a natural number, i.e., every natural number either satisfies the property or does not satisfy the property.
View a complete list of properties of natural numbers

Definition

A Riesel number is a natural number $k$ such that, for all natural numbers $n$, the number $k\cdot 2^{n}-1$ is composite.

Relation with other properties

• Sierpinski number is the analogous property for the expression $k\cdot 2^{n}+1$.