A320575 a(n) gives the number of configurations of n non-attacking rooks on an n X n chessboard such that the number of distinct distances between the rooks is given by A319476(n).

1, 2, 6, 2, 2, 28, 2, 4, 2, 8, 4, 2, 2, 4

Offset

1,2

Links

Table of n, a(n) for n=1..14.

Example

For n = 7 the a(7) = 2 boards are mirror images of each other:
  +---+---+---+---+---+---+---+
7 |   |   | * |   |   |   |   |
  +---+---+---+---+---+---+---+
6 |   |   |   |   |   | * |   |
  +---+---+---+---+---+---+---+
5 | * |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+
4 |   |   |   | * |   |   |   |
  +---+---+---+---+---+---+---+.
3 |   |   |   |   |   |   | * |
  +---+---+---+---+---+---+---+
2 |   | * |   |   |   |   |   |
  +---+---+---+---+---+---+---+
1 |   |   |   |   | * |   |   |
  +---+---+---+---+---+---+---+
    A   B   C   D   E   F   G
  +---+---+---+---+---+---+---+
7 |   |   |   |   | * |   |   |
  +---+---+---+---+---+---+---+
6 |   | * |   |   |   |   |   |
  +---+---+---+---+---+---+---+
5 |   |   |   |   |   |   | * |
  +---+---+---+---+---+---+---+
4 |   |   |   | * |   |   |   |
  +---+---+---+---+---+---+---+.
3 | * |   |   |   |   |   |   |
  +---+---+---+---+---+---+---+
2 |   |   |   |   |   | * |   |
  +---+---+---+---+---+---+---+
1 |   |   | * |   |   |   |   |
  +---+---+---+---+---+---+---+
    A   B   C   D   E   F   G

Crossrefs

Cf. A319476, A320575, A320576, A320448, A320573, A320574.

Sequence in context: A347238 A171898 A330541 * A110218 A316259 A057892

Adjacent sequences: A320572 A320573 A320574 * A320576 A320577 A320578

Keyword

nonn,more

Author

Peter Kagey, Oct 15 2018

Extensions

a(10) corrected and a(11)-a(14) from Giovanni Resta, Oct 21 2018

Status

approved