Pell & Locus Number :)

import java.util.*;
public class PellAndBell{
    static Scanner scan = new Scanner(System.in);
    public static int pell(int n)
    {
        if (n <= 2)
            return n;
        return 2 * pell(n - 1) + pell(n - 2);
    }
   public static int locus(int b){
     if(b==0)
        return 0;
     else if(b==1)
        return 1;
     else
        return locus(b-1)+locus(b-2);
   }

   public static int SwitchOperation(int n){
    switch (n) {
        case 1: System.out.print("Enter pell number: ");
                int p=scan.nextInt();
                System.out.println("Pell number is: "+pell(p));
                break;
        case 2: System.out.println("Enter locus number: ");
                int b=scan.nextInt();
                System.out.println("Bell number is: "+locus(b));
                break;
        default:
            System.out.println("No operation to perform");

    }
    return 0;
   }

    public static void main(String[] args) {
        int n;
        System.out.println("Enter operation you want:\n1. Pell number\n2. locus number");
        n=scan.nextInt();
        SwitchOperation(n);
    }
}