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.

1, 3, 30, 410, 6148, 96120, 1526700, 24425026, 392143828, 6306613690, 101505099104, 1634209596410, 26311180850268, 423567557239604, 6817440328754244, 109703307312544664, 1764863031686159684, 28385338557467333804, 456426743658724223028, 7337464027218416593362

Offset: 0

Author

Peter Kagey, Oct 25 2017

Keywords

• nonn

Comments

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

En passant capturing is not possible.

Examples

			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 |
  +---+---+---+---+
		

Links

• Code Golf Stack Exchange user feersum, Too many pawns on a chess board.

Crossrefs

Cf. A035290.