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A352623 a(n) is the maximum number k of queens that can be placed on an n X n chessboard such that, for each number j in 0..k-1, there is a queen attacking exactly j unoccupied squares. 0
0, 1, 0, 5, 8, 11, 14, 18, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
COMMENTS
On the 6 X 6 board in the illustration (see Example), each square containing a number is occupied by a queen, and the number in that square is the number of unoccupied squares attacked by that queen. (Each square with no number is unoccupied.)
Solvers:
a(4) = 8 by Rodolfo Kurchan
a(5) = 11 by Gustavo Piñeiro
a(6) = 14 by Antonio Misericordia
a(7) = 18 by Antonio Misericordia
a(8) = 22 by Giorgio Vecchi
LINKS
EXAMPLE
Solution illustrating a(6) = 14 by Antonio Misericordia:
+---+---+---+---+---+---+
| 2 | 7 | | 5 | 4 | 0 |
+---+---+---+---+---+---+
| 10| | | | 6 | 1 |
+---+---+---+---+---+---+
| | | | 11| | 3 |
+---+---+---+---+---+---+
| | | | 13| | 8 |
+---+---+---+---+---+---+
| | | | | | |
+---+---+---+---+---+---+
| | | 12| | 9 | |
+---+---+---+---+---+---+
CROSSREFS
Cf. A186238.
Sequence in context: A063247 A184928 A186238 * A314389 A363889 A118520
KEYWORD
nonn,more
AUTHOR
Rodolfo Kurchan, Mar 24 2022
STATUS
approved

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Last modified May 23 16:36 EDT 2024. Contains 372765 sequences. (Running on oeis4.)