23.2 The Fibonacci Sequence
The Fibonacci sequence is a series of numbers, starting with the pair 0 and 1, where the value of each element is calculated as the sum of the two preceding it. Hence: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1,597, 2,584, 4,181, 6,765, and so on, ad infinitum.
The ratio of each entry in the series to its next tends toward an irrational constant, known as the Golden Ratio, whose value is approximately 1.61803398875. The Golden Ratio appears to crop up in all kinds of places in the universe, from the ratio of aesthetically pleasing picture frames to the twirls of conch shells to the dimensions of the Parthenon. If you've not come across it before, I recommend you check it out.