Java Program to Print the Sum of Series 3 + 7+ 13 + 21 + … + N

In the previous article we have discussed about Java Program to Print the Sum of Series 1^2 + 2^2 + 3^2 + 4^2 + …… + N^2

In this article we are going to see how to print the sum of series 3 + 7+ 13 + 21 + … + N by using Java programming language.

Java Program to Print the Sum of Series 3 + 7+ 13 + 21 + … + N

On observing the pattern carefully, we can see

First number starts from 1, then the next term follows some logic

Example:

3+4=7

7+6=13

13+8=21 … so on

…..

+4 +6 +8 +10 +12

Let’s see different ways to print the sum of series 1+ 2 + 3 + 4 + … + N.

By Using For Loop
By Using While Loop
By Using User Defined Method

Method-1: Java Program to Print the Sum of Series 3 + 7+ 13 + 21 + … + N By Using For Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in the series.
Prompt the user to enter a number as value of n.
Let declare an integer variable say ‘result’ and initialize it to 3
Let declare another integer variable say ‘add’ and initialize it to 4
Use a for loop from i=1 to i<=n-1 where the loop is incremented by 1
Inside the for loop we will find the value of result=result+add and add=add+2
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String [] args)
    {
        //creating object of Scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the Nth term “N” ");
        int n = s.nextInt();
        int result = 3;
        int add = 4;
        //for loop to print the series
        for (int i = 1; i <= n-1; i++) 
        {
            result +=add; 
            add+=2;
        }
        System.out.print("The sum of the series is "+result);
    }
}

Output:

Enter the Nth term “N” 
5
The sum of the series is 31

Method-2: Java Program to Print the Sum of Series 3 + 7+ 13 + 21 + … + N By Using While Loop

Approach:

Create Scanner class object.
Declare an integer variable say ‘n’ which holds the number of terms in the series.
Prompt the user to enter a number as value of n.
Let declare integer variable say ‘result’, ‘add’ and initialize it to 3, 4 respectively.
Declare and initialize an integer variable i=1
Continue a while loop till i<=n-1, where i is incremented by 1
Inside while loop find the value of result = result+add and add=add+2
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String [] args)
    {
        //creating object of Scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the Nth term “N” ");
        int n = s.nextInt();
        int result=3;
        int add = 4;
        int i=1;
        while(i<=n-1)
        {
            result +=add; 
            add+=2;
            i++;
        }      
        System.out.print("The sum of the series is  "+result);
    }
}

Output:

Enter the Nth term “N” 
7
The sum of the series is 57

Method-3: Java Program to Print the Sum of Series 3 + 7+ 13 + 21 + … + N By Using User Defined Method

Approach:

Create a Scanner class object.
Prompt the user to enter the which holds the number of terms in the series.
Call a user defined method printSeries() by passing n as parameter.
Inside the method use a for loop to find the series.
Let declare integer variables say ‘result’, ‘add’ and initialize it to 3,4 respectively.
Use a for loop from i=1 to i<=n-1 incremented by 1
Inside the for loop we will find the value of result+=add and add+=2
Print the result in the series.

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
    {
        // creating object of scanner class 
        Scanner s = new Scanner(System.in);
        //Taking input of number of elements in the series
        System.out.println("Enter the value of Nth term 'N' ");
        int n = s.nextInt();
        // calling printSeries method to print the series
        printSeries(n);
    }
    
    //printSeries metthod to print the series
    public static void printSeries(int n)
    {
        int result = 3, add = 4;
        System.out.print(result);
        //for loop to print the series
        for (int i = 1; i <=n-1; i++) 
        {
            result +=add; 
            add+=2;
        } 
        System.out.print("The sum of the series is "+result);
    }
}

Output:

Enter the value of Nth term 'N' 
9
3The sum of the series is 91

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