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Solution Review : Compute nth Fibonacci Number

Explore how to implement a recursive function in Python to compute the nth Fibonacci number. Understand the base cases and recursive steps that define the Fibonacci sequence, and practice coding this solution to solidify your grasp of Python recursion.

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Solution: Use Recursion

The Fibonacci sequence is obtained by adding the previous two consecutive terms; they are defined by the sequence,

fibonacci(0) = 0 # base case 
fibonacci(1) = 1 

fibonacci(n) = fibonacci(n – 1) + fibonacci(n – 2) for n >= 2 # recursive case

For example ,

0,1,1,2,3,5,8,......

if n=2, f(n)=3

The following illustration explains the concept by calculating the fourth Fibonacci number.

The following python code demonstrates how to find the nth fibonacci number:

Python 3.10.4
def fibonacci(n):
  if n <= 1:
       return n
  else:
       return(fibonacci(n-1) + fibonacci(n-2))
print(fibonacci(4))

Let’s move on to the next problem.