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A129552 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 (symmetric solutions count only once). 1
0, 0, 0, 0, 0, 0, 1, 6, 37, 164, 1572, 13133, 122279, 1155103, 11347863, 112182378 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,8

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. A002562, A129551.

Sequence in context: A129651 A097297 A047670 * A293800 A327611 A056338

Adjacent sequences:  A129549 A129550 A129551 * A129553 A129554 A129555

KEYWORD

more,nonn

AUTHOR

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

STATUS

approved

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Last modified October 22 19:53 EDT 2019. Contains 328319 sequences. (Running on oeis4.)