structure Answers1 : A1 = struct
   (* Question 1 *)
   fun C (n,r) = if r <= 0 then 1 
                 else n * C(n-1, r-1);

  (* Question 2 - improved *)
   local 
      fun FFtriple 0 = (1,3,5)
        | FFtriple n = 
          let val (a, b, c) = FFtriple (n-1) 
           in
              (b, c, a+c+1)
          end
   in
      fun FF n = let val (a,_,_) = FFtriple n 
                  in a 
                 end
   end;

   val FF20  = FF 20
   and FF200 = FF 200;

   (* Question 3 *)
   fun G(0, b) = 1
     | G(n, b) = 
       if n <= b then 2 + G(n-1, b)
       else G(n-1, b) + G(n-1-b, b) + 1;

    (* Question 4 *)
   fun RB 0 = 1
     | RB n = RB(n-1) + RB(n div 2) + 1;

   val RB100 = RB 100;
end;