Program to find the nth term of the series -2, 4, -6, 8….

Given a number N, the task is to find the Nth term of the the following series.

-2, 4, -6, 8……

Examples:

Input: n=4
Output: 8

Input: n=3
Output: -6

Approach: By clearly examining the series we can find the Tn term for the series and with the help of tn we can find the desired result.

Tn=-2 + 4 -6 +8 …..
We can see that here odd terms are negative and even terms are positive
Tn=2(-1)nn
Tn=(-1)n2n

Below is the implementation of above approach.

CPP

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// C++ implementation of the approach
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to return the
// nth term of the given series
long Nthterm(int n)
{
  
    // nth term
    int Tn = pow(-1, n) * 2 * n;
  
    return Tn;
}
  
// Driver code
int main()
{
    int n = 3;
  
    cout << Nthterm(n);
  
    return 0;
}

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Python

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# Python3 implementation of the approach  
     
# Function to return the nth term of the given series  
def Nthterm(n):  
     
    # nth term  
    Tn = ((-1)**n) * (2 * n) 
     
    return Tn;  
     
     
# Driver code  
n = 3
print(Nthterm(n))

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Java

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// Java implementation of the approach
import java.util.*;
import java.lang.*;
import java.io.*;
  
public class GFG {
  
    // Function to return the nth term of the given series
    static int NthTerm(int n)
    {
        int Tn
            = ((int)Math.pow(-1, n)) * 2 * n;
  
        return Tn;
    }
  
    // Driver code
    public static void main(String[] args)
    {
        int n = 3;
        System.out.println(NthTerm(n));
    }
}

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C#

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// C# implementation of the approach
using System;
public class GFG {
  
    // Function to return the nth term of the given series
    static int NthTerm(int n)
    {
  
        int Tn
            = ((int)Math.Pow(-1, n) * 2 * n);
  
        return Tn;
    }
  
    // Driver code
    public static void Main()
    {
        int n = 3;
        Console.WriteLine(NthTerm(n));
    }
}

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PHP

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<?php  
// PHP implementation of the approach  
    
// Function to return the nth term of the given series  
function Nthterm($n)  
{  
    
    $Tn = (pow(-1, $n)) * (2*n);  
    
    // nth term of the given series  
    return $Tn;  
                        
}  
        
// Driver code  
$n = 3;  
echo Nthterm($n);  
?>  

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Output:

-6


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