

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
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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



