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# Python Program to Print the Natural Numbers Summation Pattern

• Last Updated : 04 Jun, 2022

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:

## Python3

 `# 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.

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