Find Nth term of the series 2, 3, 10, 15, 26….

Given a number N, the task is to find the Nth term in series 2, 3, 10, 15, 26….

Example:

Input: N = 2
Output: 3
2nd term = (2*2)-1
         = 3

Input: N = 5
Output: 26
5th term = (5*5)+1
         = 26

Approach:

  • Nth number of the series is obtained by
    1. Squaring the number itself.
    2. If the number is odd, add 1 to the squared number. And, subtract 1 if the number is even
  • Since the starting number of the series is 2

    1st term = 2
    2nd term = (2 * 2) – 1 = 3
    3rd term = (3 * 3) + 1 = 10
    4th term = (4 * 4) – 1 = 15
    5th term = (5 * 5) + 1 = 26
    and so on….

  • In general, Nth number is obtained by formula:

Below is the implementation of the above approach:

C++

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// C++ program to find Nth term
// of the series 2, 3, 10, 15, 26....
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to find Nth term
int nthTerm(int N)
{
    int nth = 0;
  
    // Nth term 
    if (N % 2 == 1)
        nth = (N * N) + 1;
    else
        nth = (N * N) - 1;
  
    return nth;
}
  
// Driver Method
int main()
{
    int N = 5;
  
    cout << nthTerm(N) << endl;
  
    return 0;
}

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Java














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// Java program to find Nth term 


// of the series 2, 3, 10, 15, 26.... 


class GFG 


{ 


  


// Function to find Nth term 


static int nthTerm(int N) 


{ 


    int nth = 0; 


  


    // Nth term  


    if (N % 2 == 1) 


        nth = (N * N) + 1; 


    else


        nth = (N * N) - 1; 


  


    return nth; 


} 


  


// Driver code 


public static void main(String[] args) 


{ 


    int N = 5; 


  


    System.out.print(nthTerm(N) +"\n"); 


  


} 


} 


  


// This code is contributed by Rajput-Ji 



















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Python3














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# Python3 program to find Nth term  


# of the series 2, 3, 10, 15, 26....  


  


# Function to find Nth term  


def nthTerm(N) :  


    nth = 0;  


  


    # Nth term  


    if (N % 2 == 1) : 


        nth = (N * N) + 1;  


    else : 


        nth = (N * N) - 1;  


  


    return nth;  


  


# Driver Method  


if __name__ == "__main__" :  


    N = 5;  


    print(nthTerm(N)) ;  


  


# This code is contributed by AnkitRai01 



















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C#














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// C# program to find Nth term 


// of the series 2, 3, 10, 15, 26.... 


using System; 


  


class GFG 


{ 


  


// Function to find Nth term 


static int nthTerm(int N) 


{ 


    int nth = 0; 


  


    // Nth term  


    if (N % 2 == 1) 


        nth = (N * N) + 1; 


    else


        nth = (N * N) - 1; 


  


    return nth; 


} 


  


// Driver code 


public static void Main(String[] args) 


{ 


    int N = 5; 


  


    Console.Write(nthTerm(N) +"\n"); 


} 


} 


  


// This code is contributed by PrinciRaj1992 



















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Output:


26







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