A129554 Number of ways to place n+3 queens and 3 pawns on an n X n board so that no two queens attack each other (symmetric solutions count only once).

0, 0, 0, 0, 0, 0, 0, 1, 6, 66, 751, 9737, 131672, 1708295

Offset

1,9

Links

Table of n, a(n) for n=1..14.

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 7 queens are placed on a 4 X 4 board, at least two queens will be adjacent and therefore mutually attacking.

Crossrefs

Cf. A002562, A129553.

Sequence in context: A131519 A022024 A186666 * A165229 A247740 A253621

Adjacent sequences: A129551 A129552 A129553 * A129555 A129556 A129557

Keyword

more,nonn

Author

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

Status

approved