A129551 Number of ways to place n+2 queens and 2 pawns on an n X n board so that no two queens attack each other.

0, 0, 0, 0, 0, 0, 4, 44, 280, 1304, 12452, 105012, 977664, 9239816, 90776620, 897446092

Offset

1,7

Links

Table of n, a(n) for n=1..16.

R. D. Chatham, The N+k Queens Problem Page.

R. D. Chatham, M. Doyle, G. H. Fricke, J. Reitmann, R. D. Skaggs and M. Wolff, Independence and Domination Separation in Chessboard Graphs, J. Combin. Math. Combin. Comput. 68 (2009), 3-17.

Example

a(4)=0 because when 6 queens are placed on a 4 X 4 board, at least two queens will be adjacent and therefore mutually attacking.

Crossrefs

Cf. A000170, A129552.

Sequence in context: A269907 A270130 A074751 * A202162 A354646 A081078

Adjacent sequences: A129548 A129549 A129550 * A129552 A129553 A129554

Keyword

more,nonn

Author

R. Douglas Chatham (d.chatham(AT)moreheadstate.edu), Apr 20 2007

Status

approved