# Find the sum of series 3, 7, 13, 21, 31….

• Difficulty Level : Medium
• Last Updated : 22 Mar, 2021

Given a number N. The task is to find the sum of below series upto nth term.

3, 7, 13, 21, 31, ….

Examples

```Input : N = 3
Output : 23

Input : N = 25
Output : 5875```

Approach:

Subtracting the above two equations, we have:

Below is the implementation of the above approach:

## C++

 `// C++ Program to find the sum of given series` `#include ``#include ` `using` `namespace` `std;` `// Function to calculate sum``int` `findSum(``int` `n)``{``    ``// Return sum``    ``return` `(n * (``pow``(n, 2) + 3 * n + 5)) / 3;``}` `// Driver code``int` `main()``{``    ``int` `n = 25;` `    ``cout << findSum(n);` `    ``return` `0;``}`

## Java

 `// Java program to find sum of``// n terms of the given series``import` `java.util.*;` `class` `GFG``{``static` `int` `calculateSum(``int` `n)``{``    ``// returning the final sum``    ``return` `(n * ((``int``)Math.pow(n, ``2``) + ``3` `*``                               ``n + ``5``)) / ``3``;``}` `// Driver Code``public` `static` `void` `main(String arr[])``{``    ``// number of terms to``    ``// find the sum``    ``int` `n = ``25``;``    ``System.out.println(calculateSum(n));``}``}` `// This code is contributed``// by Surendra_Gangwar`

## Python 3

 `# Python program to find the``# sum of given series` `# Function to calculate sum``def` `findSum(n):``    ``# Return sum``    ``return` `(n``*``(``pow``(n, ``2``)``+``3` `*` `n ``+` `5``))``/``3` `# driver code``n ``=` `25` `print``(``int``(findSum(n)))`

## C#

 `// C# program to find``// sum of n terms of``// the given series``using` `System;` `class` `GFG``{``static` `int` `calculateSum(``int` `n)``{``    ``// returning the final sum``    ``return` `(n * ((``int``)Math.Pow(n, 2) + 3 *``                               ``n + 5)) / 3;``}` `// Driver Code``public` `static` `void` `Main()``{``    ``// number of terms to``    ``// find the sum``    ``int` `n = 25;``    ``Console.WriteLine(calculateSum(n));``}``}` `// This code is contributed``// by inder_verma.`

## PHP

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## Javascript

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Output:

`5875`

Time Complexity : O(1)

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