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A294240 The number of possible ways in which 2*n^2 black pawns and 2*n^2 white pawns can be arranged on a 2n X 2n chessboard such that no pawn attacks another. 0
1, 3, 30, 410, 6148, 96120, 1526700, 24425026, 392143828, 6306613690, 101505099104, 1634209596410, 26311180850268, 423567557239604, 6817440328754244, 109703307312544664, 1764863031686159684, 28385338557467333804, 456426743658724223028, 7337464027218416593362 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

White pawns attack diagonally up and black pawns attack diagonally down.

En passant capturing is not possible.

LINKS

Table of n, a(n) for n=0..19.

Stack Exchange user feersum, Too many pawns on a chess board

EXAMPLE

For n = 1 the a(1) = 3 boards are as follows:

  +---+---+    +---+---+    +---+---+

  | W | W |    | B | W |    | W | B |

  +---+---+    +---+---+    +---+---+

  | B | B |    | W | B |    | B | W |

  +---+---+    +---+---+    +---+---+

.

An example of one of the a(2) = 30 boards is:

  +---+---+---+---+

  | W | W | W | W |

  +---+---+---+---+

  | B | W | W | W |

  +---+---+---+---+

  | B | B | W | B |

  +---+---+---+---+

  | B | B | B | B |

  +---+---+---+---+

CROSSREFS

Cf. A035290.

Sequence in context: A058831 A234506 A212425 * A007004 A276361 A218304

Adjacent sequences:  A294237 A294238 A294239 * A294241 A294242 A294243

KEYWORD

nonn

AUTHOR

Peter Kagey, Oct 25 2017

STATUS

approved

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Last modified April 18 08:37 EDT 2019. Contains 322209 sequences. (Running on oeis4.)