Fibonacci number (nonfiction)

A tiling with squares whose side lengths are successive Fibonacci numbers: 1, 1, 2, 3, 5, 8, 13 and 21.

In mathematics, the Fibonacci numbers, commonly denoted Fn, form an integer sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1.

• Fibonacci number @ Wikipedia