Rakursiq

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private int fib(int n)
        {
            if (n <= 2) return 1;
            return fib(n - 1) + fib(n - 2);
        }

        private void button3_Click(object sender, EventArgs e)
        {
            textBox2.Text = "";
            int a = int.Parse(textBox1.Text);
            for (int i = 1; i <= a; i++)
            {
                textBox2.Text += fib(i).ToString() + ",";
            }
        }

        private int suma(int n)
        {
            if (n == 1) return 1;
            return n + suma(n - 1);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox2.Text = "";
            int a = suma(int.Parse(textBox1.Text));
            textBox2.Text = a.ToString();
        }
        private int factoriel(int n)
        {
            if (n == 1) return 1;
            else
                return n * factoriel(n - 1);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            {
                textBox2.Text = "";
                int a = factoriel(int.Parse(textBox1.Text));
                textBox2.Text = a.ToString();
            }
        }
    }