# Sierpinski number

From 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 **Sierpinski number** is a natural number such that, for all natural numbers , the number is composite.

It is known that is a Sierpinski number. The Sierpinski problem asks whether this is the smallest Sierpinski number.

## Relation with other properties

- Riesel number: The analogue of Sierpinski number for the expression .