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++

filter_none

edit
close

play_arrow

link
brightness_4
code

// 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;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// 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

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# 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

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// 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

chevron_right


Output:

26


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.