# Problem 470: Super Ramvok
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.