freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-421-prime-factors-of-n151.md

---
id: 5900f5131000cf542c510024
title: 'Problem 421: Prime factors of n15+1'
challengeType: 5
forumTopicId: 302091
dashedName: problem-421-prime-factors-of-n151
---

# --description--

Numbers of the form n15+1 are composite for every integer n > 1.

For positive integers n and m let s(n,m) be defined as the sum of the distinct prime factors of n15+1 not exceeding m.

E.g. 215+1 = 3×3×11×331. So s(2,10) = 3 and s(2,1000) = 3+11+331 = 345.

Also 1015+1 = 7×11×13×211×241×2161×9091. So s(10,100) = 31 and s(10,1000) = 483. Find ∑ s(n,108) for 1 ≤ n ≤ 1011.

# --hints--

`euler421()` should return 2304215802083466200.

```js
assert.strictEqual(euler421(), 2304215802083466200);
```

# --seed--

## --seed-contents--

```js
function euler421() {

  return true;
}

euler421();
```

# --solutions--

```js
// solution required
```