(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((*read-default-float-format* 'double-float)
         (n (read))
         (k (read))
         (dp1 (make-array (list 100 100) :element-type 'double-float :initial-element 0d0))
         (dp2 (make-array (list 100 100) :element-type 'double-float :initial-element 0d0))
         (res 0d0))
    (setf (aref dp1 0 0) 1d0
          (aref dp2 0 0) 1d0)
    (loop for i from 0 below n do
          (loop for j from 0 to (* 6 n) do
                (loop for k from 1 to 6 do
                      (incf (aref dp1 (1+ i) (+ j k)) (/ (aref dp1 i j) 6)))))
    (loop for i from 0 below n do
          (loop for j from 0 to (* 6 n)
                if (< i (- n k))
                  do (loop for k from 1 to 6 do
                           (incf (aref dp2 (1+ i) (+ j k)) (/ (aref dp2 i j) 6)))
                else
                  do (loop for k from 4 to 6 do
                           (incf (aref dp2 (1+ i) (+ j k)) (/ (aref dp2 i j) 3)))))
    (loop for i from 0 to (* 6 n) do
          (loop for j from 0 below i do
                (incf res (* (aref dp1 n j) (aref dp2 n i)))))
    (format t "~f~%" res)))

(main)