# 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

3+4=7

7+6=13

13+8=21 … so on

 3 7 13 21 31 43 ….. N

+4                    +6                   +8                    +10                  +12

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

### 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;
//for loop to print the series
for (int i = 1; i <= n-1; i++)
{
}
System.out.print("The sum of the series is "+result);
}
}

Output:

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

### 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 i=1;
while(i<=n-1)
{
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

### 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++)
{
}
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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