C# .Net Fabbocani Series, Even , Odd , Prime Number checking Form Application

public partial class Form1 : Form
    {
        int x;

        public Form1()
        {
            InitializeComponent();
          
        }

    
     

        private void button1_Click_2(object sender, EventArgs e)
        {
            x = Convert.ToInt16(textBox1.Text);
            if (x % 2 == 0) { label4.Text = "number is Even"; }
            else if (x % 3 == 0) { label4.Text = "number is odd"; }
            else if (x % x == 0) { label4.Text = "number is Prime"; }
            else
            {
                label4.Text = "number is invalid";
            }
        }
    }

run

output


!--------------------------------------------------------------------------------------------------------------------!
Fabbocani Series Program in C#

Code!!
   
 using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace fabbocani_series
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
private void button1_Click(object sender, EventArgs e)
     
 {
 first = 0; second = 1;
            if (e.KeyCode == Keys.Enter)
            {
                n = Convert.ToInt32(textBox1.Text);

                for (c = 0; c < n; c++)
                {
                    if (c <= 1)
                    {
                        next = c;

                    }
                    else
                    {
                        next = first + second;
                        first = second;
                        second = next;
                    }
                    richTextBox1.Text = " , " + next + richTextBox1.Text;
                }
                richTextBox1.Text = "\nfirst " + n + "number is at fabbocanic series is:-" + richTextBox1.Text;
}
}
}