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Program to find the Nth term of series -1, 2, 11, 26, 47……
• Difficulty Level : Hard
• Last Updated : 25 Feb, 2021

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

`-1, 2, 11, 26, 47, 74, .....`

Examples:

```Input: 3
Output: 11
Explanation:
when N = 3
Nth term = ( (3 * N * N) - (6 * N) + 2 )
= ( (3 * 3 * 3) - (6 * 3) + 2 )
= 11

Input: 9
Output: 191```

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

`Nth term of the series : ( (3 * N * N) - (6 * N) + 2 )`

Below is the implementation of the above problem:
Program:

## C++

 `// CPP program to find N-th term of the series:       ``// 9, 23, 45, 75, 113, 159......         ``       ` `#include ;``using` `namespace` `std;   ``// calculate Nth term of series   ``int` `nthTerm(``int` `N)   ``{   ``    ``return` `((3 * N * N) - (6 * N) + 2);   ``}   ``     ` `// Driver Function   ``int` `main()   ``{   ``     ` `    ``// Get the value of N   ``    ``int` `N = 3;   ``     ` `    ``// Find the Nth term   ``    ``// and print it   ``    ``cout << nthTerm(N);   ``     ` `    ``return` `0;   ``}`

## Java

 `// Java program to find N-th term of the series:``// 9, 23, 45, 75, 113, 159......`` ``class` `GFG {``    ` `    ``// calculate Nth term of series``    ``static` `int` `nthTerm(``int` `N)``    ``{``        ``return` `((``3` `* N * N) - (``6` `* N) + ``2``);``    ``}``    ` `    ``// Driver code``    ``public` `static` `void` `main(String[] args) {``        ``int` `N = ``3``;``        ` `        ``// Find the Nth term``        ``// and print it``        ``System.out.println(nthTerm(N));``    ``}``}` `// This code is contributed by bilal-hungund`

## Python3

 `# Python3 program to find N-th term``# of the series:``# 9, 23, 45, 75, 113, 159......` `def` `nthTerm(N):``    ` `    ``#calculate Nth term of series``    ``return` `((``3` `*` `N ``*` `N) ``-` `(``6` `*` `N) ``+` `2``);` `# Driver Code``if` `__name__``=``=``'__main__'``:``    ``n ``=` `3` `    ``#Find the Nth term``    ``# and print it``    ``print``(nthTerm(n))` `# this code is contributed by bilal-hungund`

## C#

 `// C# program to find N-th term of the series:``// 9, 23, 45, 75, 113, 159......``using` `System;``class` `GFG``{` `// calculate Nth term of series``static` `int` `nthTerm(``int` `N)``{``    ``return` `((3 * N * N) - (6 * N) + 2);``}` `// Driver code``public` `static` `void` `Main()``{``    ``int` `N = 3;``    ` `    ``// Find the Nth term``    ``// and print it``    ``Console.WriteLine(nthTerm(N));``}``}` `// This code is contributed by inder_verma`

## PHP

 ``

## Javascript

 ``
Output:
`11`

Time Complexity: O(1)

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