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Find the Nth term of the series 14, 28, 20, 40,…..
  • Difficulty Level : Medium
  • Last Updated : 12 Apr, 2021

Given a number N  . The task is to find the N-th term in the following series: 
 

14, 28, 20, 40, 32, 64….. 
 

Examples: 
 

Input : N = 5
Output : 32

Input : N = 6
Output : 64

 

 

Approach: 
 



  1. Initialize first number with 14.
  2. Run a loop from i = 2 to N and do following steps: 
    • For Even i, double the previous term. For example if i = 2, current term will be 2*(term when i = 1), that is 2*14 = 28.
    • For Odd i, subtract 8 from the previous term.
    • Exit the loop and print the final number.

Below is the implementation of the above approach: 
 

C++




// CPP program to find the Nth term of
// the series 14, 28, 20, 40, …..
 
#include <iostream>
using namespace std;
 
// Function to find the N-th term
int findNth(int N)
{
    // initializing the 1st number
    int b = 14;
 
    int i;
 
    // loop from 2nd term to nth term
    for (i = 2; i <= N; i++) {
        // if i is even, double the
        // previous number
        if (i % 2 == 0)
            b = b * 2;
        // if i is odd, subtract 8 from
        // previous number
        else
            b = b - 8;
    }
 
    return b;
}
 
// Driver Code
int main()
{
    int N = 6;
 
    cout << findNth(N);
 
    return 0;
}

Java




// Java program to find the Nth term of
// the series 14, 28, 20, 40,
 
import java.io.*;
 
class GFG {
   
 
// Function to find the N-th term
 static int findNth(int N)
{
    // initializing the 1st number
    int b = 14;
 
    int i;
 
    // loop from 2nd term to nth term
    for (i = 2; i <= N; i++) {
        // if i is even, double the
        // previous number
        if (i % 2 == 0)
            b = b * 2;
        // if i is odd, subtract 8 from
        // previous number
        else
            b = b - 8;
    }
 
    return b;
}
 
// Driver Code
 
 
    public static void main (String[] args) {
        int N = 6;
 
    System.out.print(findNth(N));
    }
}
// This code is contributed by shs

Python 3




# Python 3 program to find the Nth term
# of the series 14, 28, 20, 40, …..
 
# Function to find the N-th term
def findNth(N):
     
    # initializing the 1st number
    b = 14
 
    # loop from 2nd term to nth term
    for i in range (2, N + 1):
     
        # if i is even, double the
        # previous number
        if (i % 2 == 0):
            b = b * 2
             
        # if i is odd, subtract 8 from
        # previous number
        else:
            b = b - 8
 
    return b
 
# Driver Code
N = 6
 
print(findNth(N))
 
# This code is contributed
# by Akanksha Rai

C#




// C# program to find the Nth term of
// the series 14, 28, 20, 40,
 
using System;
 
public class GFG{
    // Function to find the N-th term
static int findNth(int N)
{
    // initializing the 1st number
    int b = 14;
 
    int i;
 
    // loop from 2nd term to nth term
    for (i = 2; i <= N; i++) {
        // if i is even, double the
        // previous number
        if (i % 2 == 0)
            b = b * 2;
        // if i is odd, subtract 8 from
        // previous number
        else
            b = b - 8;
    }
 
    return b;
}
 
// Driver Code
     
    static public void Main (){
    int N = 6;
    Console.WriteLine(findNth(N));
    }
}
// This code is contributed by ajit

PHP




<?php
// PHP program to find the Nth term of
// the series 14, 28, 20, 40, …..
 
// Function to find the N-th term
function findNth($N)
{
    // initializing the 1st number
    $b = 14;
 
    // loop from 2nd term to nth term
    for ($i = 2; $i <= $N; $i++)
    {
        // if i is even, double the
        // previous number
        if ($i % 2 == 0)
            $b = $b * 2;
             
        // if i is odd, subtract 8 from
        // previous number
        else
            $b = $b - 8;
    }
    return $b;
}
 
// Driver Code
$N = 6;
echo findNth($N);
 
// This code is contributed by akt_mit
?>

Javascript




<script>
 
// java script program to find the Nth term of
// the series 14, 28, 20, 40, …..
 
// Function to find the N-th term
function findNth(N)
{
    // initializing the 1st number
    let b = 14;
 
    // loop from 2nd term to nth term
    for (let i = 2; i <= N; i++)
    {
        // if i is even, double the
        // previous number
        if (i % 2 == 0)
            b = b * 2;
             
        // if i is odd, subtract 8 from
        // previous number
        else
            b = b - 8;
    }
    return b;
}
 
// Driver Code
N = 6;
document.write(findNth(N));
 
// This code is contributed
// by pulamolu mohan pavan cse
</script>
Output: 
64

 

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