---
id: 5900f3e01000cf542c50fef2
title: 'Problem 114: Counting block combinations I'
challengeType: 5
forumTopicId: 301740
dashedName: problem-114-counting-block-combinations-i
---

# --description--

A row measuring seven units in length has red blocks with a minimum length of three units placed on it, such that any two red blocks (which are allowed to be different lengths) are separated by at least one black square. There are exactly seventeen ways of doing this.

<img class="img-responsive center-block" alt="Possible ways of placing block with a minimum length of three units, on a row with length of seven units" src="https://cdn.freecodecamp.org/curriculum/project-euler/counting-block-combinations-i.png" style="background-color: white; padding: 10px;" />

How many ways can a row measuring fifty units in length be filled?

**Note:** Although the example above does not lend itself to the possibility, in general it is permitted to mix block sizes. For example, on a row measuring eight units in length you could use red (3), black (1), and red (4).

# --hints--

`countingBlockOne()` should return `16475640049`.

```js
assert.strictEqual(countingBlockOne(), 16475640049);
```

# --seed--

## --seed-contents--

```js
function countingBlockOne() {

  return true;
}

countingBlockOne();
```

# --solutions--

```js
// solution required
```
