freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-419-look-and-say-sequence.md

---
id: 5900f5101000cf542c510022
title: 'Problem 419: Look and say sequence'
challengeType: 5
forumTopicId: 302088
dashedName: problem-419-look-and-say-sequence
---

# --description--

The look and say sequence goes 1, 11, 21, 1211, 111221, 312211, 13112221, 1113213211, ...

The sequence starts with 1 and all other members are obtained by describing the previous member in terms of consecutive digits.

It helps to do this out loud:

1 is 'one one' → 11

11 is 'two ones' → 21

21 is 'one two and one one' → 1211

1211 is 'one one, one two and two ones' → 111221

111221 is 'three ones, two twos and one one' → 312211

...

Define A(n), B(n) and C(n) as the number of ones, twos and threes in the n'th element of the sequence respectively. One can verify that A(40) = 31254, B(40) = 20259 and C(40) = 11625.

Find A(n), B(n) and C(n) for n = 1012. Give your answer modulo 230 and separate your values for A, B and C by a comma. E.g. for n = 40 the answer would be 31254,20259,11625

# --hints--

`euler419()` should return 998567458, 1046245404, 43363922.

```js
assert.strictEqual(euler419(), 998567458, 1046245404, 43363922);
```

# --seed--

## --seed-contents--

```js
function euler419() {

  return true;
}

euler419();
```

# --solutions--

```js
// solution required
```