
COMMENTS

Let the squares of a standard (8 X 8) chessboard be numbered sequentially from 1 to 64, row by row (e.g., a1 = 1, b1 = 2, ..., a2 = 9, ..., h8 = 64). Let X be the number of a square a king stands on, and Y the number of a square to which it can move. Then this sequence lists all possible values of YX.
The terms are independent of the precise numbering scheme, provided that the numbers of the four possible neighbors of a square differ by + 1 in one direction and + 8 in the other direction. For example, one could also use number = row + 8 * column, where row and column range from 1 to 8, or from 0 to 7.
