The Fibonacci sequence, named after a 13th Century Italian mathematician, is a sequence of numbers in which every third number is the sum of the previous two numbers. This photo circulating the Internet shows pigeons who have landed in roughly that pattern.
via Geekosystem | Math Explanation | Previously: Fibonacci Rings
Need to remove "third" from that sentence, or, to be perfectly accurate, change it to "every number from the third onward." (The first two numbers in the series can't be the sum of the preceding two numbers, because each is preceded by fewer than two.)