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# Program to find Nth term of the series 3 , 5 , 21 , 51 , 95 , …

• Difficulty Level : Medium
• Last Updated : 15 Mar, 2021

Given a number N, the task is to find the Nth term of this series:

3, 5, 21, 51, 95, ….

Examples:

```Input: N = 4
Output: 51
Explanation:
Nth term = (7 * pow(N, 2) - 19 * N + 15)
= (7 * pow(4, 2) - 19 * 4 + 15)
= 51

Input: N = 10
Output: 525```

Approach:
The Nth term of the given series can be generalized as:

`[Tex] [/Tex]`

Below is the implementation of the above approach:

## C++

 `// CPP program to find N-th term of the series:``// 3, 5, 21, 51, 95,...` `#include ``#include ``using` `namespace` `std;` `// calculate Nth term of series``int` `getNthTerm(``long` `long` `int` `N)``{``    ``// Return Nth term``    ``return` `(7 * ``pow``(N, 2) - 19 * N + 15);``}` `// driver code``int` `main()``{``    ``// declaration of number of terms``    ``long` `long` `int` `N = 4;` `    ``// Get the Nth term``    ``cout << getNthTerm(N);` `    ``return` `0;``}`

## Java

 `// Java program to find N-th term of the series:``// 3, 5, 21, 51, 95,...``import` `java.util.*;` `class` `solution``{``static` `long` `getNthTerm(``long` `N)``{``// Return Nth term``    ``return` `(``7` `*(``int``) Math.pow(N, ``2``) - ``19` `* N + ``15``);``}` `//Driver program``public` `static` `void` `main(String arr[])``{``// declaration of number of terms``    ``long` `N = ``4``;` `    ``// Get the Nth term``     ``System.out.println(getNthTerm(N));``}``}`

## Python3

 `# Python3 program to find N-th term``# of the series:``# 3, 5, 21, 51, 95,...` `# calculate Nth term of series``def` `getNthTerm(N):``    ` `    ``#Return Nth term``    ``return` `(``7` `*` `pow``(N, ``2``) ``-` `19` `*` `N ``+` `15``)``    ` `#Driver code``if` `__name__``=``=``'__main__'``:``    ` `#declaration of number of terms``    ``N ``=` `4` `#Get the Nth term``    ``print``(getNthTerm(N))` `#this code is contributed by Shashank_Sharma`

## C#

 `// C# program to find``// N-th term of the series:``// 3, 5, 21, 51, 95,...``using` `System;` `class` `GFG``{``static` `long` `getNthTerm(``long` `N)``{``    ``// Return Nth term``    ``return` `(7 *(``int``) Math.Pow(N, 2) -``                       ``19 * N + 15);``}` `// Driver Code``static` `public` `void` `Main ()``{` `    ``// declaration of number``    ``// of terms``    ``long` `N = 4;` `    ``// Get the Nth term``    ``Console.Write(getNthTerm(N));``}``}` `// This code is contributed by Raj`

## PHP

 ``

## Javascript

 ``
Output:
`51`

Time Complexity: O(1)

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