Procedure Fibonacci(n)
  Static NewMap Fib.i()
  Protected FirstRecursion

  If MapSize(Fib())= 0        ; Init the hash table the first run
    Fib("0")=0: Fib("1")=1
    FirstRecursion = #True
  EndIf

  If n >= 2
    Protected.s s=Str(n)
    If Not FindMapElement(Fib(),s)  ; Calculate only needed parts
      Fib(s)= Fibonacci(n-1)+Fibonacci(n-2)
    EndIf
    n = Fib(s)
  EndIf
  If FirstRecursion ; Free the memory when finalizing the first call
    ClearMap(Fib())
  EndIf
  ProcedureReturn n
EndProcedure