# Fibonacci Series in Python – Iterative and Recursive Approaches

In Python programming, the Fibonacci series is a classic mathematical sequence that starts with 0 and 1, where each subsequent number is the sum of the two preceding numbers. The Fibonacci series is often used as an exercise in programming to demonstrate different techniques and approaches. In this blog post, we will explore two methods for generating the Fibonacci Sequence in Python: using a FOR loop and recursion. We will provide examples to illustrate each approach’s implementation and discuss their advantages and considerations.

What is Fibonacci series in Python?

The Fibonacci series in Python is a sequence of numbers where each number is the sum of the two preceding ones, starting from 0 and 1. It typically begins as: 0, 1, 1, 2, 3, 5, 8, 13, 21, and so on. The Fibonacci sequence is commonly generated using iteration or recursion and finds applications in various mathematical and programming contexts.

## Generating Fibonacci Series using a FOR Loop:

Using a FOR loop is an iterative approach to generate the Fibonacci fib series. We initialize the first two numbers of the series, and then, for each subsequent number, we calculate it as the sum of the previous two numbers.

Example: Generating Fibonacci series using a FOR loop:

``````def fibonacci_for_loop(n):
series = []
a, b = 0, 1
for _ in range(n):
series.append(a)
a, b = b, a + b
return series

fib_sequence = fibonacci_for_loop(10)
print("Fibonacci series (FOR loop):", fib_sequence)``````

Output:

``Fibonacci series (FOR loop): [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]``

## Generating Fibonacci Series using Recursion

Using recursion is a more elegant but potentially less efficient approach to generate the Fibonacci series. In this approach, we define a function that calls itself to calculate the Fibonacci number at a given position.

Example: Generating Fibonacci series using recursion:

``````def fibonacci_recursive(n):
if n <= 1:
return n
else:
return fibonacci_recursive(n - 1) + fibonacci_recursive(n - 2)

fib_sequence = [fibonacci_recursive(i) for i in range(10)]
print("Fibonacci series (recursion):", fib_sequence)``````

Output:

``Fibonacci series (recursion): [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]``