A279405 Peaceable coexisting armies of queens on a torus: the maximum number m such that m white queens and m black queens can coexist on an n X n toroidal chessboard without attacking each other.

0, 0, 0, 2, 2, 4, 4, 8, 7, 12, 10, 18

Offset

1,4

Comments

a(n) <= A250000(n).

a(n) is maximal m such that A279406(n,m) >= m.

Links

Table of n, a(n) for n=1..12.

Andy Huchala, Python program.

Katie Clinch, Matthew Drescher, Tony Huynh, and Abdallah Saffidine, Constructions, bounds, and algorithms for peaceable queens, arXiv:2406.06974 [math.CO], 2024. See p. 1.

Example

A solution for n=6:
......
.W...W
...B..
..B.B.
...B..
.W...W

Crossrefs

Cf. A250000, A279406.

Sequence in context: A191234 A225373 A138219 * A100835 A347444 A120541

Adjacent sequences: A279402 A279403 A279404 * A279406 A279407 A279408

Keyword

nonn,hard,more

Author

Andrey Zabolotskiy, Dec 11 2016

Extensions

a(10)-a(12) from Andy Huchala, Mar 10 2024

Status

approved