Работа с одномерными списками - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
namespace L_2
{
 
    class LinkedListVector
    {
 
        class Node
        {
             private double a = 0;
             private Node next = null;  
 
             public double A
             {
                 get;
                 set;
             }
             public Node Next
             {
                 get;
                 set;
             }
 
             public Node(double a, Node next)
             {
                 Next = next;
                 A = a;
             }
            public Node ()
            {
                }
        }
 
        private Node first;
        private Node last;
 
        public LinkedListVector(int a)
        {
            Node tec = new Node();
            if (first != null)
            {
                for (int i = 0; i < a; i++)
                {
                    tec.Next = last;
                    last = tec;
                }
            }
        }
 
        public double this[int i]
        {
            
            get
            {
                
                if (i == 0)
                {
                    Node tec = new Node();
                    first = last = tec;
                    first.Next = tec;
                    return tec.A;
                }
                else
                {
                    Node tec = new Node();
                    last.Next = tec;
                    last = tec;
                    return tec.A;
 
                }
            }
            set
            {
                Node tec = new Node();
                last.Next = tec;
                last = tec;
                value = tec.A;
 
            }
        }
 
        public void Print()
        {
            Node tec = first;
            while (tec != null)
            {
                Console.Write("\t" + tec.A);
                tec = tec.Next;
            }
        }
 
    }
}