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A321534 a(n) gives the number of configurations of non-attacking rooks up to symmetry on an n X n chessboard such that the number of distinct directions between the rooks is given by A321531(n). 0
1, 1, 1, 1, 2, 21, 11, 74, 89, 18 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

Conjecture: a(n) = A321532(n)/8 for n >= 4.

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

For n = 5, the a(5) = 2 essentially different configurations of nonattacking rooks with the maximal number of directions between them are given by the following two chessboards:

   +---+---+---+---+---+

  5| X |   |   |   |   |

   +---+---+---+---+---+

  4|   |   | X |   |   |

   +---+---+---+---+---+

  3|   |   |   | X |   |

   +---+---+---+---+---+

  2|   |   |   |   | X |

   +---+---+---+---+---+

  1|   | X |   |   |   |

   +---+---+---+---+---+

     A   B   C   D   E

   +---+---+---+---+---+

  5| X |   |   |   |   |

   +---+---+---+---+---+

  4|   |   |   | X |   |

   +---+---+---+---+---+

  3|   |   | X |   |   |

   +---+---+---+---+---+

  2|   |   |   |   | X |

   +---+---+---+---+---+

  1|   | X |   |   |   |

   +---+---+---+---+---+

     A   B   C   D   E

CROSSREFS

Cf. A321531, A321532.

Sequence in context: A298822 A072397 A077208 * A212483 A084313 A074769

Adjacent sequences:  A321531 A321532 A321533 * A321535 A321536 A321537

KEYWORD

nonn,more

AUTHOR

Peter Kagey, Nov 12 2018

STATUS

approved

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Last modified October 23 19:26 EDT 2021. Contains 348215 sequences. (Running on oeis4.)