Program to find Nth term of series 1, 6, 17, 34, 56, 86, 121, 162, …….

Given a number N. The task is to write a program to find the Nth term of the below series:

1, 6, 17, 34, 56, 86, 121, 162, …..(N Terms)

Examples:

Input: N = 4
Output: 34
For N = 4
4th Term = ( 3 * 4 * 4 - 4 * 4 + 2) 
         = 34

Input: N = 10
Output: 261



Approach: The generalized Nth term of this series:

 nth\: Term\: of\: the\: series\: = 3*n^2-4*n+2  

Below is the required implementation:

C++

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// C++ program to find the N-th term of the series:
// 1, 6, 17, 34, 56, 86, 121, 162, .....
#include <iostream>
#include <math.h>
using namespace std;
  
// calculate Nth term of series
int nthTerm(int n)
{
    return 3 * pow(n, 2) - 4 * n + 2;
}
  
// Driver code
int main()
{
    int N = 4;
  
    cout << nthTerm(N) << endl;
  
    return 0;
}

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Java

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// Java program to find the N-th term of the series: 
// 1, 6, 17, 34, 56, 86, 121, 162, ..... 
  
public class GFG {
      
    // calculate Nth term of series 
    static int nthTerm(int n) 
    
        return 3 * (int) Math.pow(n, 2) - 4 * n + 2
    
        
    // Driver code
    public static void main(String args[])
    {
        int N = 4
            
       System.out.println(nthTerm(N)); 
      
    }
    // This Code is contributed by ANKITRAI1
}
  

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Python3

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# Python program to find the 
# N-th term of the series:
# 1, 6, 17, 34, 56, 86, 121, 162, .....
  
# calculate Nth term of series
def nthTerm(n):
  
    return 3 * pow(n, 2) - 4 * n + 2
  
# Driver code
N = 4
print(nthTerm(N))
  
# This code is contributed by
# Sanjit_Prasad

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C#

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// C# program to find the
// N-th term of the series: 
// 1, 6, 17, 34, 56, 86, 121, 162, ..... 
using System;
class GFG 
{
      
// calculate Nth term of series 
static int nthTerm(int n) 
    return 3 * (int) Math.Pow(n, 2) - 
                         4 * n + 2; 
      
// Driver code
public static void Main()
{
    int N = 4; 
          
    Console.Write(nthTerm(N)); 
}
}
  
// This code is contributed 
// by ChitraNayal

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PHP

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<?php 
// PHP program to find the 
// N-th term of the series:
// 1, 6, 17, 34, 56, 86, 121, 162, .....
  
// calculate Nth term of series
function nthTerm($n)
{
    return 3 * pow($n, 2) - 
           4 * $n + 2;
}
  
// Driver code
$N = 4;
  
echo nthTerm($N)."\n";
  
// This code is contributed 
// by ChitraNayal
?>

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Output:

34

Time Complexity: O(1)



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