Find nth term of the series 2, 8, 18, 32, 50, . . . .

Given an integer N, the task is to find the Nth term of the series 

2,  8,  18,  32,  50, ….till N terms

Examples:

Input: N = 4 
Output: 32

Input: N = 6
Output: 72

Approach:

From the given series, find the formula for Nth term-

1st term = 2 * 1 ^ 2 = 2

2nd term = 2 * 2 ^ 2 = 8

3rd term = 2 * 3 ^ 2 = 18

4th term = 2 * 4 ^ 2 = 32

.

.

Nth term = 2 * N ^ 2

The Nth term of the given series can be generalized as-

T_N = 2 * N ^ 2

Illustration:

Input: N = 6
Output: 72
Explanation:
T_N= 2 * N ^ 2
    = 2 * 6 ^ 2
    = 72

Below is the implementation of the above approach-

C++

// C++ program to implement
// the above approach
#include <iostream>
using namespace std;

// Function to return nth
// term of the series
int find_nth_Term(int n) { return 2 * n * n; }

// Driver code
int main()
{
    // Value of N
    int N = 6;

    // function call
    cout << find_nth_Term(N) << endl;
    return 0;
}

Java

// Java program for the above approach
import java.io.*;
import java.lang.*;
import java.util.*;

class GFG {

    // Function to return nth
    // term of the series
    static int find_nth_Term(int n) { return 2 * n * n; }

    // Driver code
    public static void main(String[] args)
    {

        // Value of N
        int N = 6;

        // function call
        System.out.println(find_nth_Term(N));
    }
}

// This code is contributed by hrithikgarg03188.

Python

# Python program to implement
# the above approach

# Find n-th term of series
# 2, 8, 18, 32, 50...


def nthTerm(n):

    return 2 * n * n


# Driver Code
if __name__ == "__main__":

    # Value of N
    N = 6

    # function call
    print(nthTerm(N))

# This code is contributed by Samim Hossain Mondal.

C#

// C# program to implement
// the above approach
using System;

class GFG {

    // Function to return nth
    // term of the series
    static int find_nth_Term(int n) { return 2 * n * n; }

    // Driver Code
    public static void Main()
    {

        // Value of N
        int N = 6;

        // function call
        Console.Write(find_nth_Term(N));
    }
}

// This code is contributed by sanjoy_62.

Javascript

<script>
        // JavaScript code for the above approach

        // Function to return nth
        // term of the series
        function find_nth_Term(n) {
            return 2 * n * n;
        }

        // Driver code

        // Value of N
        let N = 6;

        // function call
        document.write(find_nth_Term(N) + '<br>');

       // This code is contributed by Potta Lokesh
    </script>

Output

72

Time Complexity: O(1) 
Auxiliary Space: O(1)