Python Program to Find Sum of Natural Numbers Using Recursion

Here in this article, we have provided a python source code that can find the sum of the first n natural numbers using recursion technique.

Prerequisite Python Program to Find Sum of Natural Numbers Using Recursion

• Python Input, Output
• Python User-Defined Function
• Python Recursion
• Python if…else statements

Steps:

• First, ask the user to enter a number.
• create a function in which, with each recursion, we decrease the number value by one.
• And add the decremented number with the actual number itself.

Python Program to Find Sum of Natural Numbers Using Recursion

Python Code

def first_sum(n):
    if n <= 1:
        return n
    else:
        #recursion
        return n + first_sum(n-1)

num = int(input("Enter the Number: "))

if num > 0:
    print("The sum of first", num, "is ",first_sum(num))
else:
    print("Please Enter a valid number")

Output 1:

Enter the Number: 18
The sum of first 18 is 171

Output 2:

Enter the Number: 4
The sum of first 4 is 10

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