Fibonacci sequence

The Fibonacci sequence is a sequence of numbers, called Fibonacci numbers, where each number is the sum of the two previous numbers in the sequence. The only exception is the first two numbers which are 0 and 1.

Formal definition:

F(0) := 0 F(1) := 1 F(n) := F(n - 2) + F(n - 1) where n > 1

Writing a program that calculates Fibonacci numbers is a popular problem when trying out a new esoteric language, or for showcasing its features.

External resources

 * Fibonacci sequence on Wikipedia