Find nth term of the series 3, 8, 15, 24, . . .

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

3, 8, 15, 24, . . .till Nth term

Examples:

Input: N = 5 
Output: 35

Input: N = 6
Output: 48

Approach:

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

1st term  = 1 (1 + 2) = 3

2nd term = 2 (2 + 2) = 8

3rd term =  3 (3 + 2) = 15

4th term =  4 (4 + 2) = 24

.

.

Nth term = N * (N + 2) 

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

T_N = N * (N + 2)

Illustration:

Input: N = 5
Output: 35
Explanation:
T_N = N * (N + 2)
     = 5 * (5 + 2)
     = 35

Below is the implementation of the above approach-

C++

// C++ program to find nth term
// of the series
#include <iostream>
using namespace std;

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

// Driver code
int main()
{
    // Find given nth term
    int N = 5;

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

Java

// Java program to find nth term
// of the series
class GFG
{

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

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

    // Find given nth term
    int N = 5;

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

// This code is contributed by gfgking

Python

# Python program to find nth
# term of the series

# Function to return nth
# term of the series
def find_nth_Term(n):

    return n * (n + 2)


# Driver code

# Find given nth term
n = 5

# Function call
print(find_nth_Term(n))

# This code is contributed by Samim Hossain Mondal.

C#

// C# program to find nth term
// of the series
using System;
class GFG
{

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

  // Driver code
  public static int Main()
  {

    // Find given nth term
    int N = 5;

    // Function call
    Console.WriteLine(find_nth_Term(N));
    return 0;
  }
}

// This code is contributed by Taranpreet

Javascript

<script>
       // JavaScript code for the above approach

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

       // Driver code

       // Find given nth term
       let N = 5;

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

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

Output

35

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