# Find Nth term of the series 0, 2, 4, 8, 12, 18…

Given a number N. The task is to write a program to find the Nth term in the below series:

0, 2, 4, 8, 12, 18…

Examples:

```Input: 3
Output: 4
For N = 3
Nth term = ( 3 + ( 3 - 1 ) * 3 ) / 2
= 4
Input: 5
Output: 12
```

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

On observing carefully, the Nth term in the above series can be generalized as:

`Nth term = ( N + ( N - 1 ) * N ) / 2`

Below is the implementation of the above approach:

## C++

 `// CPP program to find N-th term of the series: ` `// 0, 2, 4, 8, 12, 18... ` `#include ` `using` `namespace` `std; ` ` `  `// Calculate Nth term of series ` `int` `nthTerm(``int` `N) ` `{ ` `    ``return` `(N + N * (N - 1)) / 2; ` `} ` ` `  `// Driver Function ` `int` `main() ` `{ ` `    ``int` `N = 5; ` ` `  `    ``cout << nthTerm(N); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find N-th term of the series: ` `// 0, 2, 4, 8, 12, 18... ` `import` `java.io.*; ` ` `  `// Main class for main method ` `class` `GFG { ` `    ``public` `static` `int` `nthTerm(``int` `N) ` `    ``{ ` `        ``// By using above formula ` `        ``return` `(N + (N - ``1``) * N) / ``2``; ` `    ``}    ` `  `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `N = ``5``; ``// 5th term is 12 ` `             `  `        ``System.out.println(nthTerm(N)); ` `    ``} ` `} `

## Python 3

 `# Python 3 program to find N-th term of the series:  ` `# 0, 2, 4, 8, 12, 18. ` ` `  `# Calculate Nth term of series ` `def` `nthTerm(N) : ` `     `  `    ``return` `(N ``+` `N ``*` `(N ``-` `1``)) ``/``/` `2` ` `  `# Driver Code ` `if` `__name__ ``=``=` `"__main__"` `: ` ` `  `    ``N ``=` `5` ` `  `    ``print``(nthTerm(N)) ` ` `  `# This code is contributed by ANKITRAI1 `

## C#

 `// C# program to find N-th term of the series: ` `// 0, 2, 4, 8, 12, 18... ` `using` `System; ` `class` `gfg ` `{    ` `    ``// Calculate Nth term of series ` `    ``public` `int` `nthTerm(``int` `N) ` `    ``{ ` `        ``int` `n = ((N + N * (N - 1)) / 2); ` `        ``return` `n; ` `    ``} ` ` `  `    ``//Driver program ` `    ``static` `void` `Main(``string``[] args) ` `    ``{ ` `        ``gfg p = ``new` `gfg(); ` `        ``int` `a = p.nthTerm(5); ` `        ``Console.WriteLine(a); ` `        ``Console.Read(); ` `    ``} ` `} ` `//This code is contributed by SoumikMondal `

## PHP

 ` `

Output:

```12
```

Time Complexity: O(1)

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