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A090051 Number of chess diagrams that can be obtained in exactly one way in n plies. This is also the number of dual-free proof games in n plies. 5
1, 20, 400, 1862, 9373, 51323, 298821, 1965313, 11759158, 66434263, 365037821, 1895313862 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 22 22:38 EST 2018. Contains 298093 sequences.