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

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

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```

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

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## Javascript

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Output:
`12`

Time Complexity: O(1)

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