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# Find N-th term of series 2, 8, 18, 32, 50…

Given the series 2, 8, 18, 32, 50…, find the Nth term of the series.

Examples:

Input: N = 1
Output: 2

Input: N = 3
Output: 18

Input: N = 5
Output: 50

Approach:

For finding the nth term we need to find the relation between n and each term.

1st term = 2 =  2*(12) // 2*first perfect square

2nd term = 8 = 2*(22) // 2*second perfect square

3rd term = 18 = 2*(32) //  2*third perfect square

4th term = 32 = 2*(42) //  2*fourth perfect square

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Nth term = 2*(Nth perfect square)

Formula-

TN = 2 * N ^ 2

Illustration-

Input: N = 5
Output: 50
Explanation-
TN = 2 * N ^ 2
= 2* 5 ^ 2
= 2 * 25
= 50

Below is the C++ program to implement the above approach-

## C++

 `// C++ program to implement` `// the above approach` `#include ` `using` `namespace` `std;`   `// Find n-th term of series` `// 2, 8, 18, 32, 50...` `int` `nthTerm(``int` `N)` `{`   `    ``// Nth perfect square is N * N` `    ``int` `Nthperfectsquare = N * N;`   `    ``return` `2 * Nthperfectsquare;` `}` `// Driver code` `int` `main()` `{` `    ``int` `N = 5;`   `    ``cout << nthTerm(N) << endl;` `    ``return` `0;` `}`

## Java

 `// Java code for the above approach`   `import` `java.io.*;`   `class` `GFG {` `  `  `// Find n-th term of series` `// 2, 8, 18, 32, 50...` `static` `int` `nthTerm(``int` `N)` `{`   `    ``// Nth perfect square is N * N` `    ``int` `Nthperfectsquare = N * N;`   `    ``return` `2` `* Nthperfectsquare;` `}` `// Driver code` `    ``public` `static` `void` `main (String[] args) {` `      `  `       ``int` `N = ``5``;`   `        ``System.out.println(nthTerm(N));` `    ``}` `}` `// This code is contributed by Potta Lokesh`

## Python

 `# Python program to implement` `# the above approach`   `# Find n-th term of series` `# 2, 8, 18, 32, 50...` `def` `nthTerm(N):`   `    ``# Nth perfect square is N * N` `    ``Nthperfectsquare ``=` `N ``*` `N`   `    ``return` `2` `*` `Nthperfectsquare`   `# Driver Code` `if` `__name__ ``=``=` `"__main__"``:` `  `  `    ``N ``=` `5` `    `  `    ``print``(nthTerm(N))`   `# This code is contributed by Samim Hossain Mondal.`

## C#

 `using` `System;`   `public` `class` `GFG{`   `// Find n-th term of series` `// 2, 8, 18, 32, 50...` `static` `int` `nthTerm(``int` `N)` `{`   `    ``// Nth perfect square is N * N` `    ``int` `Nthperfectsquare = N * N;`   `    ``return` `2 * Nthperfectsquare;` `}`   `// Driver code` `static` `public` `void` `Main (){`   `    ``int` `N = 5;` `    ``Console.Write(nthTerm(N));` `}` `}`   `// This code is contributed by hrithikgarg03188`

## Javascript

 ``

Output:

`50`

Time Complexity: O(1), since there is no loop or recursion.
Auxiliary Space: O(1), since no extra space has been taken.

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