# Find the Nth term of the series 5, 13, 37, 109, 325, . . .

• Last Updated : 21 Sep, 2022

Given a positive integer N. The task is to find Nth term of the series 5, 13, 37, 109, 325, …..

Examples:

Input: N = 5
Output: 325
Explanation:  From the sequence it can be seen that the 5th term is 325

Input: N = 1
Output: 5
Explanation: The 1st term of the given sequence is 5

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

TN = 4 * 3N – 1 + N

Below is the implementation of the above approach:

## C++

 `// C++ program to implement` `// the above approach` `#include ` `using` `namespace` `std;`   `// Function to return Nth term` `// of the series` `int` `calcNum(``int` `N) ` `{ ` `  ``return` `4 * ``pow``(3, N - 1) + 1; ` `}`   `// Driver Code` `int` `main()` `{` `    ``int` `N = 5;`   `    ``cout << calcNum(N);` `    ``return` `0;` `}`

## Java

 `// Java program to implement` `// the above approach` `import` `java.util.*;` `public` `class` `GFG` `{`   `  ``// Function to return Nth term` `  ``// of the series` `  ``static` `int` `calcNum(``int` `N) ` `  ``{ ` `    ``return` `4` `* (``int``)Math.pow(``3``, N - ``1``) + ``1``; ` `  ``}`   `  ``// Driver Code` `  ``public` `static` `void` `main(String args[])` `  ``{` `    ``int` `N = ``5``;` `    ``System.out.println(calcNum(N));` `  ``}` `}`   `// This code is contributed by Samim Hossain Mondal.`

## Python3

 `# Python 3 program for the above approach`   `# Function to return Nth term` `# of the series` `def` `calcNum(N):` `    `  `    ``return` `4` `*` `pow``(``3``, N ``-` `1``) ``+` `1`   `# Driver Code` `if` `__name__ ``=``=` `"__main__"``:`   `    ``N``=``5`   `    ``print``(calcNum(N))`   `# This code is contributed by Abhishek Thakur.`

## C#

 `// C# program to implement` `// the above approach` `using` `System;`   `public` `class` `GFG{`   `  ``// Function to return Nth term` `  ``// of the series` `  ``static` `int` `calcNum(``int` `N) ` `  ``{ ` `    ``return` `4 * (``int``)Math.Pow(3, N - 1) + 1; ` `  ``}`   `  ``// Driver Code` `  ``static` `public` `void` `Main ()` `  ``{` `    ``int` `N = 5;` `    ``Console.Write(calcNum(N));` `  ``}` `}`     `// This code is contributed by SHubham Singh`

## Javascript

 ``

Output

`325`

Time Complexity: O(log2N), where N represents the given integer.
Auxiliary Space: O(1), no extra space is required.

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