Fibonacci numbers are a sequence of numbers that are made by taking 0 and 1, and adding them together to get 1, so you have 0, 1, and 1. Then,take the 1 and 1, and add them together to get 2, so you now have 0, 1, 1, and 2. Next add the 2 and 1 to get 3, giving you 0, 1, 1, 2, and 3.

Using concise mathematical notation, if $F_n$ is the $n^{th}$ Fibonacci number, given that $F_0=0$ and $F_1=1$, then $F_n=F_{n-1}+F_{n-2}$.

This sequence is a good lesson-base for writing a function, so let's do that here.

Let's write a function that will print the sequence of Fibonacci numbers. We'll call the function fib(n), where n is a number we pass the function, telling it how many Fibonacci numbers we want it to print. So we'd call it by programming fib(10) to see the first 10 Fibonacci numbers (past the initial 0 and 1, etc.).