

A209433


Number of chess diagrams that can be obtained in n plies, but not in fewer plies.


1



1, 20, 400, 5202, 69731, 766337, 8708079, 86540204, 880526165, 7996545696, 73802185449, 616052245142
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OFFSET

0,2


COMMENTS

Chess diagrams are chess positions without regard to whether castling or en passant capturing is possible. The condition that the diagram cannot be obtained in fewer than n plies means that each legal chess diagram is counted exactly once in this sequence, indexed by the length of the shortest game(s) to reach it. Therefore, this sequence is finite and its sum equals the number of legal chess diagrams, estimated to be between 10^43 and 10^47.


LINKS

Table of n, a(n) for n=0..11.
F. Labelle, Statistics on chess positions
Index entries for sequences related to number of chess games


CROSSREFS

Cf. A019319, A209080.
Sequence in context: A207091 A223988 A189698 * A188988 A019319 A083276
Adjacent sequences: A209430 A209431 A209432 * A209434 A209435 A209436


KEYWORD

nonn,hard,fini,more


AUTHOR

François Labelle, Mar 08 2012


EXTENSIONS

a(11) from François Labelle, Feb 27 2017


STATUS

approved



