# Discrete Functions

### Terms

Combination Function  -  C(n, k) = .
Discrete Function  -  A function that is defined only for a set of numbers that can be listed, such as the set of whole numbers or the set of integers.
Explicit Definition  -  A definition of a function by a formula in terms of the variable.
Factorial Function  -  F(n) = n(n - 1)(n - 2)(n - 3) ... (2)(1)
where n is a non-negative integer.
We define F(0) = 1 and F(1) = 1 .
Fibonacci Sequence  -  The sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, ..., where each value is the sum of the preceding two values. Defined recursively by:

Permutation Function  -  P(n, k) =
Recursive Definition  -  A definition of a function in terms of the same function of a smaller variable.

## Take a Study Break

### Star Trek gets SEXY

Chris Pine and Zoe Saldana heat up the red carpet!

### Are you afraid of relationships?

Auntie SparkNotes can help!

### Sexy starlet style

See every single look from the Met Gala!

### Geeky Actors: Then and Now

Travel back in time!

### Villains We Want These Actresses to Play

From super cute to super bad!

### 10 Movies Better Than Their Books

What do you think?

### How To Look Like J-Law...

When you don't look like J-Law.

### 12 Scientific Inaccuracies in Into Darkness

What did Star Trek get wrong?

## The Book

### Read What You Love, Anywhere You Like

Get Our FREE NOOK Reading Apps