Fibonacci numbers are a sequence of numbers in which each number is the sum of the two numbers that come before it. For example, the first number in the sequence is 1, then the next number is 1 (1+0), then the next number is 2 (1+1), then the next number is 3 (2+1), and so on. So the sequence is: 1, 1, 2, 3, 5, 8, 13, 21, 34, and so on.