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A309260
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Number of ways of placing 2n-1 nonattacking rooks on a hexagonal board with edge-length n in Glinski's hexagonal chess, inequivalent up to rotations and reflections of the board.
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5
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1, 1, 1, 5, 29, 224, 3012, 55200, 1259794, 35488536, 1200819600
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refs;
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OFFSET
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1,4
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COMMENTS
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A rook in Glinski's hexagonal chess can move to any cell along the perpendicular bisector of any of the 6 edges of the hexagonal cell it's on (analogous to a rook in orthodox chess which can move to any cell along the perpendicular bisector of any of the 4 edges of the square cell it's on).
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LINKS
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EXAMPLE
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a(1) = 1
.
o
.
a(2) = 1
.
o .
. . o
o .
.
a(3) = 1
.
o . .
. . o .
. . . . o
o . . .
. o .
.
a(4) = 5
.
o . . . o . . . o . . . . o . . . o . .
. . o . . . . o . . . . . o . o . . . . . . . . o
. . . . o . . . . . . o . . . . . o . . . . . o o . . . . .
. . . . . . o . o . . . . . . . o . . . . . . . o . . . . . . o . . .
o . . . . . . . . . . o o . . . . . . . . . . o . . . . . o
. o . . . . . o . . . . . . o o . . . . o . . . .
. . o . o . . . . o . . . o . . . . o .
.
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CROSSREFS
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KEYWORD
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nonn,more,hard
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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