# Program to find the Nth term of series -1, 2, 11, 26, 47……

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
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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:

 `// 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 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 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# 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 `

 ` `

Output:
```11
```

Time Complexity: O(1)

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