---
id: 5900f4c21000cf542c50ffd4
challengeType: 5
title: 'Problem 340: Crazy Function'
---
## Description
For fixed integers a, b, c, define the crazy function F(n) as follows:
F(n) = n - c for all n > b
F(n) = F(a + F(a + F(a + F(a + n)))) for all n ≤ b.
Also, define S(a, b, c) = .
For example, if a = 50, b = 2000 and c = 40, then F(0) = 3240 and F(2000) = 2040.
Also, S(50, 2000, 40) = 5204240.
Find the last 9 digits of S(217, 721, 127).
## Instructions
## Tests
```yml
tests:
- text: euler340() should return 291504964.
testString: 'assert.strictEqual(euler340(), 291504964, "euler340() should return 291504964.");'
```
## Challenge Seed
```js
function euler340() {
// Good luck!
return true;
}
euler340();
```