

A090051


Number of chess diagrams that can be obtained in exactly one way in n plies. This is also the number of dualfree proof games in n plies.


5



1, 20, 400, 1862, 9373, 51323, 298821, 1965313, 11759158, 66434263, 365037821, 1895313862
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OFFSET

0,2


COMMENTS

Chess diagrams are chess positions without regard to whether castling or en passant capturing is possible. They are counted in A019319. A proof game is a classic type of chess problem.


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, A089957, A209080.
Sequence in context: A208017 A208559 A209080 * A089957 A267718 A207402
Adjacent sequences: A090048 A090049 A090050 * A090052 A090053 A090054


KEYWORD

nonn,hard,nice,fini


AUTHOR

François Labelle, Jan 19 2004


EXTENSIONS

a(9)a(10) from Arkadiusz Wesolowski, Jan 04 2012
a(11) from François Labelle, Jan 16 2017


STATUS

approved



