public List<int> BaseNumbers = new List<int> { 1, 1, 2, 3, 5, 8 };
        public int GetFibnaceNumber(List<int> baseNumbers, int len)
        {
            if (len <= 2)
            {
                return 1;
            }
            else if ((len - 1) <= BaseNumbers.Count)
            {
                len = len - 1;
                return BaseNumbers[len - 1] + BaseNumbers[len - 2];
            }
            else
            {
                int BaseMaxIndex = BaseNumbers.Count;
                BaseNumbers.Add(BaseNumbers[BaseMaxIndex - 1] + BaseNumbers[BaseMaxIndex - 2]);
                return GetFibnaceNumber(BaseNumbers, len);
            }
        }
//csharp/5637