# Find Nth term of the series 1, 6, 18, 40, 75, ….

• Difficulty Level : Easy
• Last Updated : 22 Jun, 2022

Given a number n, the task is to find the n-th term in series 1, 6, 18, 40, 75, …
Example:

```Input: N = 2
Output: 6
Explanation:
2nd term = (2^2*(2+1))/2
= 6

Input: N = 5
Output: 75
Explanation:
5th term = (5^2*(5+1))/2
= 75```

Approach:

Nth term = (N^2*(N+1))/2

Implementation of the above approach is given below:

## C++

 `// CPP code to generate``// 'Nth' term of this sequence` `#include ``using` `namespace` `std;` `// Function to generate a fixed number``int` `nthTerm(``int` `N)``{``    ``int` `nth = 0;` `    ``//(N^2*(N+1))/2``    ``nth = (N * N * (N + 1)) / 2;` `    ``return` `nth;``}` `// Driver Method``int` `main()``{``    ``int` `N = 5;` `    ``cout << nthTerm(N) << endl;` `    ``return` `0;``}`

## Java

 `// Java code to generate``// 'Nth' term of this sequence` `class` `GFG {` `    ``// Function to generate a fixed number``    ``public` `static` `int` `nthTerm(``int` `N)``    ``{``        ``int` `nth = ``0``;` `        ``//(N^2*(N+1))/2``        ``nth = (N * N * (N + ``1``)) / ``2``;` `        ``return` `nth;``    ``}` `    ``// Driver Method``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `N = ``5``;` `        ``System.out.println(nthTerm(N));``    ``}``    ``// This code is contributed by 29AjayKumar``}`

## Python3

 `# python program to find out'Nth' term of this sequence` `# Function to generate a fixed number``def` `nthTerm(N):``    ``nth ``=` `0``    ``nth ``=` `(N ``*` `N ``*` `(N ``+` `1``))``/``/``2``    ``return` `nth` `# Driver code``N ``=` `5``print``(nthTerm(N))` `# This code is contributed by Shrikant13`

## C#

 `// C# code to generate``// 'Nth' term of this sequence` `using` `System;``public` `class` `GFG {` `    ``// Function to generate a fixed number``    ``public` `static` `int` `nthTerm(``int` `N)``    ``{``        ``int` `nth = 0;` `        ``//(N^2*(N+1))/2``        ``nth = (N * N * (N + 1)) / 2;` `        ``return` `nth;``    ``}` `    ``// Driver Method``    ``public` `static` `void` `Main(``string``[] args)``    ``{``        ``int` `N = 5;` `        ``Console.WriteLine(nthTerm(N));``    ``}``}` `// This code is contributed by Shrikant13`

## PHP

 ``

## Javascript

 ``

Output:

`75`

Time Complexity: O(1)

Auxiliary Space: O(1)

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