---
title: Investigating the primality of numbers of the form 2n2-1
---
## Problem 216: Investigating the primality of numbers of the form 2n2-1

This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/coding-interview-prep/project-euler/problem-216-investigating-the-primality-of-numbers-of-the-form-2n2-1/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.

<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.

<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->