# Python Program for the Sum of Natural Numbers using Recursion

In this tutorial, we will discuss a Python program for the sum of natural numbers using recursion.

Before going to the program first, let us understand what is *Natural Numbers.*

**Natural Numbers:**

- Natural numbers are all positive integers from 1 to infinity.
- The sum of the first $n$ natural numbers is given by the formula: $S=2n(n+) $, but we will use recursion to achieve this.

**Related:** Python program for Simple Interest Calculation

#### Program code for the sum of natural numbers using recursion in Python

# Sum of Natural Numbers Using Recursion in Python def sum_of_natural_numbers(n): if n == 1: return 1 else: return n + sum_of_natural_numbers(n - 1) number = int(input("Enter a positive integer: ")) if number < 1: print("Please enter a positive integer.") else: print(f"The sum of the first {number} natural numbers is {sum_of_natural_numbers(number)}.")

#### Explanation

**Function Definition**: The`sum_of_natural_numbers`

function takes an integer`n`

as input and returns the sum of the first $n$ natural numbers using recursion.**Main Program**: The program prompts the user to enter a positive integer and then calculates the sum of the first $n$ natural numbers using the`sum_of_natural_numbers`

function and prints the result.

#### Output

- When you run the above program, it will prompt you to enter a positive integer.
- After entering the number, it will calculate the sum of the first $n$ natural numbers using recursion and print the result.

#### Conclusion

- In this tutorial, we learned how to find the sum of the first $n$ natural numbers using a recursive approach in a Python program.
- Understanding this concept is essential for solving various mathematical problems and enhancing your programming skills.