be 64 . 63 . ... . 57.

As far as it's the "number of sequences", there is no problem, but it is

confused with "state space size" in the next paragraphs, while this

doesn't take into account the the arrangements with less than 8 queens

(1, 2, ..., 7) and also the fact that most of the states are repeated.

So, I'm guessing that the state space size should be:

64/1! + (64 . 63)/2! + ... + (64 . 63 . ... . 57)/8!