id:A090051 - OEIS Search Results

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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.

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4

1, 20, 400, 1862, 9373, 51323, 298821, 1965313, 11759158 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`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	`F. Labelle, Statistics on chess positions` `Index entries for sequences related to number of chess games`
	CROSSREFS	`Cf. A019319, A089957.` `Sequence in context: A097832 A063815 A075843 this_sequence A089957 A019319 A083276` `Adjacent sequences: A090048 A090049 A090050 this_sequence A090052 A090053 A090054`
	KEYWORD	`nonn,hard,nice`
	AUTHOR	`Francois Labelle (flab(AT)cs.berkeley.edu), Jan 19 2004`

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Last modified July 26 23:19 EDT 2008. Contains 142293 sequences.