Longest Collatz sequence

Problem 14.cs

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

namespace EulerProject
{
    class Program
    {
        private static Dictionary<long, long> CollatzLengths;

        [STAThread]
        static void Main(string[] args)
        {
            CollatzLengths = new Dictionary<long, long>();

            long highestLength = 0;

            for (long i = 1; i < 1000000; i++)
            {
                Console.WriteLine(i);
                Console.CursorTop--;

                long length = findCollatzLength(i);

                if(length > highestLength)
                {
                    highestLength = length;
                    Console.WriteLine("Highest Length is now {0} for {1}", highestLength, i);
                }
            }
            Console.ReadLine();
        }

        public static long findCollatzLength(long number)
        {
            long amount = 0;

            while(number != 1)
            {
                if(CollatzLengths.ContainsKey(number))
                {
                    return amount + CollatzLengths[number];
                }
                else
                { 
                    amount++;

                    if (number % 2 == 0)
                    {
                        number = number / 2;
                    }
                    else
                    {
                        number = (3 * number) + 1;
                    }
                }
            }
            return amount;
        }
    }
}