The Fibonacci Sequence

In 1202, Leonardo of Pisa — Fibonacci — posed a puzzle about breeding rabbits whose population followed a simple rule: each month, the new total was the sum of the previous two. The sequence 1, 1, 2, 3, 5, 8, 13… now bears his name, and it surfaces in sunflower spirals, pineapple skins, pine cones, hurricane clouds, and the painting of the Renaissance. One recurrence, and nature can't stop using it.