The Fibonacci Numbers

One special recursively defined function, which has no simple explicit definition, yields the Fibonacci numbers:


The values of this function are:


f (1)=1  
f (2)=1  
f (3)=1 + 1 = 2  
f (4)=1 + 2 = 3  
f (5)=2 + 3 = 5  
f (6)=3 + 5 = 8  
f (7)=5 + 8 = 13  
f (8)=8 + 13 = 21  
f (9)=13 + 21 = 34  
    

Thus, the sequence of Fibonacci numbers is 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, . These numbers have many interesting properties that will be studied in higher math. They recur often in mathematics and even in nature.