freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-304-primonacci.md

---
id: 5900f49d1000cf542c50ffaf
title: 'Problem 304: Primonacci'
challengeType: 5
forumTopicId: 301958
dashedName: problem-304-primonacci
---

# --description--

For any positive integer n the function next_prime(n) returns the smallest prime p such that p>n.

The sequence a(n) is defined by: a(1)=next_prime(1014) and a(n)=next_prime(a(n-1)) for n>1.

The fibonacci sequence f(n) is defined by: f(0)=0, f(1)=1 and f(n)=f(n-1)+f(n-2) for n>1.

The sequence b(n) is defined as f(a(n)).

Find ∑b(n) for 1≤n≤100 000. Give your answer mod 1234567891011.

# --hints--

`euler304()` should return 283988410192.

```js
assert.strictEqual(euler304(), 283988410192);
```

# --seed--

## --seed-contents--

```js
function euler304() {

  return true;
}

euler304();
```

# --solutions--

```js
// solution required
```