%N Number of possible chess games at the end of the n-th ply starting without knights.
%C Gives the number of possible chess games where both sides start without knights. Knights are still allowed to appear later in the game through promotion.
%C Does not include games which end in fewer than n plies.
%C The total number of such games should be less than the total number of standard chess games, and it appears A285875(n) <= A048987(n) for all n.
%C Initial terms computed using the Chesspresso engine.
%H <a href="http://www.chesspresso.org/">Chesspresso<sup>TM</sup></a>.
%e a(1) = 18 because each pawn can move forward 1 or 2 squares (16 moves) and each rook can move into the square where the knight would have been (2 moves).
%Y Cf. A048987 (standard), A285873 (no queens), A285874 (no rooks), A285876 (no bishops), A285877 (no pawns), A285878 (pawns and king).
%A _Sean A. Irvine_, Apr 28 2017