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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 Table of n, a(n) for n=0..8. Rodolfo Kurchan, Chess Puzzle Fun 5 Uneven Attacks 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 Adjacent sequences: A352620 A352621 A352622 * A352624 A352625 A352626 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.)