OFFSET
0,2
COMMENTS
Gives the number of possible chess games where both sides start without queens. Queens are still allowed to appear later in the game through promotion.
Does not include games which end in fewer than n plies.
The total number of such games should be less than the total number of standard chess games, and it appears A285873(n) <= A048987(n) for n >= 7.
Initial terms computed using the Chesspresso engine.
EXAMPLE
a(1) = 21 because there are 20 usual opening moves plus the additional move of moving the king into the vacant square where the queen would usually be.
CROSSREFS
KEYWORD
nonn,hard,more,fini
AUTHOR
Sean A. Irvine, Apr 28 2017
STATUS
approved