login
A368061
The number of ways to place one pawn and n+1 nonattacking queens on an n X n chessboard, unchanged by 180-degree rotation.
1
0, 0, 0, 0, 0, 0, 1, 0, 5, 0, 18, 0, 50, 0, 652, 0, 4260, 0, 25134, 0, 238098, 0, 2492304, 0, 25389294
OFFSET
1,9
COMMENTS
n must be odd, and the pawn must be in the center.
FORMULA
A103330(n) = 8*A103331(n) - 4*a(n).
EXAMPLE
For n=7 the a(7)=1 solution is
. . Q . . . .
. . . . . Q .
. . . Q . . .
Q . . P . . Q
. . . Q . . .
. Q . . . . .
. . . . Q . .
CROSSREFS
A103330 counts all solutions; A103331 counts them with symmetry removed.
Sequence in context: A367191 A093782 A085105 * A094031 A022902 A291926
KEYWORD
nonn,more
AUTHOR
Don Knuth, Dec 10 2023
STATUS
approved