def problem470():
    """


    Consider a single game of Ramvok:

       Let t represent the maximum number of turns the game lasts. If t = 0, then
       the game ends immediately. Otherwise, on each turn i, the player rolls a
       die. After rolling, if i < t the player can either stop the game and
       receive a prize equal to the value of the current roll, or discard the
       roll and try again next turn. If i = t, then the roll cannot be discarded
       and the prize must be accepted. Before the game begins, t is chosen by the
       player, who must then pay an up-front cost ct for some constant c. For c =
       0, t can be chosen to be infinite (with an up-front cost of 0). Let R(d,
       c) be the expected profit (i.e. net gain) that the player receives from a
       single game of optimally-played Ramvok, given a fair d-sided die and cost
       constant c. For example, R(4, 0.2) = 2.65. Assume that the player has
       sufficient funds for paying any/all up-front costs.

       Now consider a game of Super Ramvok:

       In Super Ramvok, the game of Ramvok is played repeatedly, but with a
       slight modification. After each game, the die is altered. The alteration
       process is as follows: The die is rolled once, and if the resulting face
       has its pips visible, then that face is altered to be blank instead. If
       the face is already blank, then it is changed back to its original value.
       After the alteration is made, another game of Ramvok can begin (and during
       such a game, at each turn, the die is rolled until a face with a value on
       it appears). The player knows which faces are blank and which are not at
       all times. The game of Super Ramvok ends once all faces of the die are
       blank.

       Let S(d, c) be the expected profit that the player receives from an
       optimally-played game of Super Ramvok, given a fair d-sided die to start
       (with all sides visible), and cost constant c. For example, S(6, 1) =
       208.3.

       Let F(n) = ∑[4≤d≤n] ∑[0≤c≤n] S(d, c).

       Calculate F(20), rounded to the nearest integer.
    """
    pass
