Java Program to Print the Series -1 4 -7 10 -13 16 -19 … N

In the previous article, we have discussed about Java Program to Find the Sum of Series 1!/1 + 2!/2 + 3!/3 + 4!/4+ 5!/5 + N!/N

In this article we are going to see how to print the series print series -1 4 -7 10 -13 16 -19 … N by using java programming language.

Java Program to Print the Series -1 4 -7 10 -13 16 -19 … N

On observing the pattern carefully, we can see Odd numbers are assigned -ve sign and even number assigned to +ve sign.

The numbers in the series are added by 3 with respect to the previous number.

For example:

-1

-7

-13

-19

-25

1 1+3 4+3 7+3 10+3 13+3 16+3 19+3 22+3

Let’s see different ways to print the series -1 4 -7 10 -13 16 -19 … N

By Using for Loop
By Using User Defined Method

Method-1: Java Program to Print the Series -1 4 -7 10 -13 16 -19 … N By Using for Loop

Approach:

Declare an int variable say ‘n’ which holds the nth value of the series.
Create Scanner class object.
Prompt the user to enter a number as value of n.
Use a for loop and iterate from i=1 to i<=n
Inside loop by taking if-else statement check the number if it is even number then print it as +i if the number is odd number then print it as -i where ‘i‘ is the number.

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 number of elements of the series: ");
    int n=s.nextInt();
    //declaring int variable a and initializing its value as 1
    int a=1; 
    //for loop to print the series
    for(int i = 1; i<=n; i++)
      {
       //checking if the value is even then print it with + symbol
       if(i%2==0)
       {
           System.out.print(a+" ");
       }
       //else the value is odd and printing it with - symbol
       else
       {
           System.out.print(-1*a+" ");
       }
       //increasing the value a by 3
       a+=3;
      }
   }
}

Output:

Enter number of elements of the series: 
5
-1 4 -7 10 -13

Method-2: Java Program to Print the Series -1 4 -7 10 -13 16 -19 … N By Using User Defined Method

Approach:

Here the logic is same just implement that with in a user defined method.

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 number of elements of the series: ");
    int n=s.nextInt();
    //declaring int variable a and initializing its value as 1
    int a=1;
    //calling a user defined method 
    printSeries(n,a);
   }
   
   //method to print the series
   public static void printSeries(int n, int a)
   {
    //for loop to print the series
    for(int i = 1; i<=n; i++)
      {
       //checking if the value is even then print it with + symbol
       if(i%2==0)
       {
           System.out.print(a+" ");
       }
       //else the value is odd and printing it with - symbol
       else
       {
           System.out.print(-1*a+" ");
       }
       //increasing the value a by 3
       a+=3;
      }
   }
}

Output:

Enter number of elements of the series: 
55
-1 4 -7 10 -13

Explore complete java concepts from the Java programming examples and get ready to become a good programmer and crack the java software developer interview with ease.

Related Java Programs: