You need 16^16 for 32768 because 0 is used to represent an empty tile (2^0 = 1 is not used) which is exactly equal to 2^64. The state in this implementation al

You need 16^16 for 32768 because 0 is used to represent an empty tile (2^0 = 1 is not used) which is exactly equal to 2^64. The state in this implementation also stores a random seed (between 0 and 99, exclusive), so using 16^16 for the state would leave nothing for the random seed.