---
id: 5900f4431000cf542c50ff56
challengeType: 5
title: 'Problem 215: Crack-free Walls'
---

## Description
<section id='description'>
Consider the problem of building a wall out of 2×1 and 3×1 bricks (horizontal×vertical dimensions) such that, for extra strength, the gaps between horizontally-adjacent bricks never line up in consecutive layers, i.e. never form a "running crack".

For example, the following 9×3 wall is not acceptable due to the running crack shown in red:




There are eight ways of forming a crack-free 9×3 wall, written W(9,3) = 8.

Calculate W(32,10).
</section>

## Instructions
<section id='instructions'>

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler215()</code> should return 806844323190414.
    testString: assert.strictEqual(euler215(), 806844323190414, '<code>euler215()</code> should return 806844323190414.');

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function euler215() {
  // Good luck!
  return true;
}

euler215();
```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```
</section>