# Exercise XX - fibonacci

Create a function that returns a specific member of the fibonacci sequence:

> a series of numbers in which each number ( Fibonacci number ) is the sum of the two preceding numbers. The simplest is the series 1, 1, 2, 3, 5, 8, etc.

```javascript
fibonacci(4) // returns the 4th member of the series: 3  (1, 1, 2, 3)
fibonacci(6) // returns 8
```