freeCodeCamp/curriculum/challenges/spanish/08-coding-interview-prep/project-euler/problem-447-retractions-c.spanish.md

---
id: 5
localeTitle: 5900f52c1000cf542c51003e
challengeType: 5
title: 'Problem 447: Retractions C'
---

## Description
<section id='description'> 
Para cada entero n&gt; 1, la familia de funciones fn, a, b se define 
por fn, a, b (x) ≡ax + b mod n para a, b, x entero y 0 <a<n, 0≤b<n, 0≤x<n.<code> 0 Llamaremos retracción de fn, a, ba si fn, a, b (fn, a, b (x)) ≡fn, a, b (x) mod n para cada 0≤x <n.<code> 0 Sea R (n) el número de retracciones para n. 


F (N) = ∑R (n) para 2≤n≤N. 
F (107) ≡638042271 (mod 1 000 000 007). 


Encuentra F (1014) (mod 1 000 000 007). 
</section>

## Instructions
<section id='instructions'> 

</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler447()</code> debe devolver 530553372.
    testString: 'assert.strictEqual(euler447(), 530553372, "<code>euler447()</code> should return 530553372.");'

```

</section>

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

<div id='js-seed'>

```js
function euler447() {
  // Good luck!
  return true;
}

euler447();
```

</div>



</section>

## Solution
<section id='solution'>

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