5 + 8 = 13


Smokestack in Turku, Finland


This problem was studied and solved by a famous mathematician, Fibonacci. The numbers of rabbits form the Fibonacci series. This series has important applications in several problems that have nothing to do with rabbits. Call the N'th number in the series fib(N):

Fibonacci Series
N12345 678910
fib(N)11235 813213455

Here is the rule for filling the chart, rewritten for fib(N):

fib( N ) = fib( N-1 ) + fib( N-2 )

Look at the chart to verify that the rule works.


Is the rule a correct recursive definition?