Generating fibonacci sequence and creating subsets for it

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication
{
    class Program
    {
        static IEnumerable<long> fibs = Enumerable.Empty<long>();
        static int count, fromIndex, toIndex;
        static void Main(string[] args)
        {
            while (true)
            {
                Generate();
                Console.Write(string.Format("Enter index range between 0 and {0}\n", count));
                Console.Write("Enter first index : ");
                fromIndex = int.Parse(Console.ReadLine());
                Console.Write("Enter last index : ");
                toIndex = int.Parse(Console.ReadLine());
                GenerateSubset(fromIndex, toIndex);
            }
        }
        public static void Generate()
        {
            int i;
            long f1 = 0, f2 = 1, f3 = 0;
            Console.Write("Enter the Limit : ");
            count = int.Parse(Console.ReadLine());
            //Console.WriteLine(f1);
            //Console.WriteLine(f2);
            fibs = fibs.Concat(new[] { f2 });
            Console.Write("Full sequence :\n");
            Console.WriteLine(f2);
            for (i = 0; i < count; i++)
            {
                f3 = f1 + f2;
                fibs = fibs.Concat(new[] { f3 });
                Console.WriteLine(f3);
                f1 = f2;
                f2 = f3;
            }
        }

        static public void GenerateSubset(int fromIndex, int toIndex)
        {
            for (int i = fromIndex; i <= toIndex; i++)
            {
                Console.WriteLine(fibs.ElementAt(i));
            }
            Console.WriteLine("\n");
        }
    }
}