Python Program to Print the Natural Numbers Summation Pattern

Given a natural number n, the task is to write a Python program to first find the sum of first n natural numbers and then print each step as a pattern.

Input: 5

Output:

1 = 1
1 + 2 = 3
1 + 2 + 3 = 6
1 + 2 + 3 + 4 = 10
1 + 2 + 3 + 4 + 5 = 15

Input: 10

Output:

1 = 1

1 + 2 = 3

1 + 2 + 3 = 6

1 + 2 + 3 + 4 = 10

1 + 2 + 3 + 4 + 5 = 15

1 + 2 + 3 + 4 + 5 + 6 = 21

1 + 2 + 3 + 4 + 5 + 6 + 7 = 28

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55

Approach:

• Take Input n.
• Use two loops:
  • j ranging between 1 to n.
  • i ranging between 1 to j.
• Print the value of i and ‘+’ operator while appending the value of i to a list.
• Then Find the Sum of Elements in the List.
• Print "=" with Total Sum.
• Exit.

Program:

# Inputing Natural Number
number = int(input("Enter the Natural Number: "))
# j ranges from 1 to n
for j in range(1, number+1):
    # Initializing List
    a = []
    # i loop ranges from 1 to j
    for i in range(1, j+1):
        print(i, sep=" ", end=" ")
        if(i < j):
            print("+", sep=" ", end=" ")
        a.append(i)
    print("=", sum(a))
print()

Output:

Enter the Natural Number: 5

1 = 1

1 + 2 = 3

1 + 2 + 3 = 6

1 + 2 + 3 + 4 = 10

1 + 2 + 3 + 4 + 5 = 15

Time Complexity: O(n²), where n represents the given input.
Auxiliary Space: O(1), no extra space is required, so it is a constant.