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 A328283 The maximum number m such that m white, m black and m red queens can coexist on an n X n chessboard without attacking each other. 1
 0, 0, 0, 1, 1, 2, 3, 4, 5, 7, 8, 10, 12, 14 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS This is the peaceable queens problem (A250000) for 3 players. For n >= 11, it seems that a(n) is simply 2n - 14. However this turns out to be false as a(18) >= 23. LINKS Dmitry Kamenetsky, Best known solutions for n <= 24. Arthur O'Dwyer, Discrete Peaceful Encampments, 2019. Arthur O'Dwyer, Discrete Peaceful Encampments: Player 3 has entered the game!, Puzzling StackExchange, 2019. EXAMPLE a(8) = 4, because 4 queens of each color can co-exist without attacking queens of another color. Note that in this case red has more than 4 queens. + - - - - - - - - + | . . W W . . . . | | . . W W . . . . | | . . . . . . R R | | . . . . . . . R | | . . . . R . . . | | B B . . . . . . | | B B . . . . . . | | . . . . R R R R | + - - - - - - - - + CROSSREFS Cf. A250000. Sequence in context: A062469 A340758 A238098 * A034156 A034157 A135675 Adjacent sequences:  A328280 A328281 A328282 * A328284 A328285 A328286 KEYWORD nonn,more,hard AUTHOR Dmitry Kamenetsky, Oct 11 2019 STATUS approved

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Last modified May 21 00:36 EDT 2022. Contains 353886 sequences. (Running on oeis4.)