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.

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

Offset: 0

Author

François Labelle, Jan 19 2004

Keywords

• nonn
• hard
• more
• nice
• fini

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

• F. Labelle, Statistics on chess positions
• Index entries for sequences related to number of chess games

Crossrefs

Cf. A019319, A089957, A209080.

Extensions

a(9)-a(10) from Arkadiusz Wesolowski, Jan 04 2012

a(11) from François Labelle, Jan 16 2017