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A309260 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. 4
1, 1, 1, 5, 29, 224, 3012, 55199, 1259765 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

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).

LINKS

Table of n, a(n) for n=1..9.

Chess variants, Glinski's Hexagonal Chess

Vaclav Kotesovec, All inequivalent solutions for n = 2,3,4 and 5

Wikipedia, Hexagonal chess - GliƄski's hexagonal chess

EXAMPLE

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 .

.

CROSSREFS

Cf. A000903, A002047, A003215, A309746, A309669.

Sequence in context: A094856 A057623 A182018 * A087662 A113012 A000354

Adjacent sequences:  A309257 A309258 A309259 * A309261 A309262 A309263

KEYWORD

nonn,more

AUTHOR

Sangeet Paul, Jul 19 2019

EXTENSIONS

a(8) from Vaclav Kotesovec, Aug 16 2019

a(9) from Vaclav Kotesovec, Aug 23 2019

STATUS

approved

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Last modified May 16 03:46 EDT 2021. Contains 343937 sequences. (Running on oeis4.)