---
id: 5900f5271000cf542c51003a
challengeType: 5
title: 'Problem 443: GCD sequence'
forumTopicId: 302115
localeTitle: 'Задача 443: последовательность GCD'
---
## Description
Let g(n) be a sequence defined as follows:
g(4) = 13,
g(n) = g(n-1) + gcd(n, g(n-1)) for n > 4.
The first few values are:
n 4567891011121314151617181920...
g(n) 1314161718272829303132333451545560...
You are given that g(1 000) = 2524 and g(1 000 000) = 2624152.
Find g(1015).
## Instructions
## Tests
```yml
tests:
- text: euler443() should return 2744233049300770.
testString: assert.strictEqual(euler443(), 2744233049300770);
```
## Challenge Seed
```js
function euler443() {
// Good luck!
return true;
}
euler443();
```