1:  namespace FibonacciSequence {
   2:      using System;
   3:   
   4:      class Program {
   5:          static void Main() {
   6:              ulong previous = 1;
   7:              ulong current = 1;
   8:              Console.Write(current + "\n");
   9:   
  10:              while (current < 10000000000000000000) {
  11:                  Console.Write(current + "\n");
  12:   
  13:                  ulong next = current + previous;
  14:                  previous = current;
  15:                  current = next;
  16:              }
  17:              Console.ReadKey();
  18:          }       
  19:      }
  20:  }