# Find the sum of N terms of the series 1/1*3, 1/3*5, 1/5*7, ….

• Last Updated : 14 Feb, 2022

Given a positive integer, N. Find the sum of the first N term of the series-

1/1*3, 1/3*5, 1/5*7, ….

Examples:

Input: N = 3

Output: 0.428571

Input: N = 1

Output: 0.333333

Approach: The sequence is formed by using the following pattern. For any value N-

SN = N / (2 * N + 1)

Below is the implementation of the above approach:

## C++

 `// C++ program to implement``// the above approach` `#include ``using` `namespace` `std;` `// Function to return sum of``// N term of the series` `double` `findSum(``int` `N) {``  ``return` `(``double``)N / (2 * N + 1);``}` `// Driver Code` `int` `main()``{``    ``int` `N = 3;` `    ``cout << findSum(N);``}`

## Java

 `// JAVA program to implement``// the above approach``import` `java.util.*;``class` `GFG``{` `  ``// Function to return sum of``  ``// N term of the series``  ``public` `static` `double` `findSum(``int` `N)``  ``{``    ``return` `(``double``)N / (``2` `* N + ``1``);``  ``}` `  ``// Driver Code``  ``public` `static` `void` `main(String[] args)``  ``{``    ``int` `N = ``3``;` `    ``System.out.print(findSum(N));``  ``}``}` `// This code is contributed by Taranpreet`

## Python3

 `# Python 3 program for the above approach` `# Function to return sum of``# N term of the series` `def` `findSum(N):``  ``return` `N ``/` `(``2` `*` `N ``+` `1``)`  `# Driver Code``if` `__name__ ``=``=` `"__main__"``:``  ` `    ``# Value of N``    ``N ``=` `3`   `    ``print``(findSum(N))` `# This code is contributed by Abhishek Thakur.`

## C#

 `// C# program to implement``// the above approach``using` `System;``class` `GFG``{` `  ``// Function to return sum of``  ``// N term of the series``  ``public` `static` `double` `findSum(``int` `N)``  ``{``    ``return` `(``double``)N / (2 * N + 1);``  ``}` `  ``// Driver Code``  ``public` `static` `void` `Main()``  ``{``    ``int` `N = 3;` `    ``Console.Write(findSum(N));``  ``}``}` `// This code is contributed by gfgking`

## Javascript

 ``

Output

`0.428571`

Time Complexity: O(1)
Auxiliary Space: O(1)

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