code: def LL(n):
      
      if (n<=0):return Context('0')
      else:
          LL1=LL(n-1)
          r1 = C1(3**(n-1),2**(n-1)) - LL1 - LL1
          r2 = LL1 - LL1 - LL1
          return r1 + r2
docs: constructs the LL context