A285874 - OEIS

A285874

Number of possible chess games at the end of the n-th ply starting without rooks.

1, 20, 400, 8702, 188473, 4505624, 106770421, 2770746488, 71151220765, 1969755500063

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OFFSET

0,2

COMMENTS

Gives the number of possible chess games where both sides start without rooks. Rooks 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 A285874(n) <= A048987(n) for all n.

Initial terms computed using the Chesspresso engine.

LINKS

Bernhard Seybold, Chesspresso.

CROSSREFS

Cf. A048987 (standard), A285873 (no queens), A285875 (no knights), A285876 (no bishops), A285877 (no pawns), A285878 (pawns and king).

KEYWORD

nonn,hard,more,fini

AUTHOR

EXTENSIONS

a(9) from Sean A. Irvine, May 04 2017

STATUS

approved