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A352661
Number of doubly symmetric characteristic solutions to the n-superqueens problem.
4
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0, 12, 17, 0, 0, 60, 82
OFFSET
1,12
COMMENTS
Superqueens are also called amazons. They combine the moves of queen and knight.
REFERENCES
Martin Gardner, Fractal Music, Hypercards, and More, W H Freeman, 1991, page 238 (based on his column in Scientific American, June 1979).
D. E. Knuth, The Art of Computer Programming, Section 7.2.2.3 (draft, March 2022).
EXAMPLE
For n=12 the a(12)=2 solutions are
+-------------------------+ +-------------------------+
| . . . . A . . . . . . . | | . . . . A . . . . . . . |
| . . . . . . . . . A . . | | . . . . . . . . . A . . |
| . A . . . . . . . . . . | | . A . . . . . . . . . . |
| . . . . . A . . . . . . | | . . . . . . A . . . . . |
| . . . . . . . . . . . A | | . . . . . . . . . . . A |
| . . . . . . . . A . . . | | . . . A . . . . . . . . |
| . . . A . . . . . . . . | | . . . . . . . . A . . . |
| A . . . . . . . . . . . | | A . . . . . . . . . . . |
| . . . . . . A . . . . . | | . . . . . A . . . . . . |
| . . . . . . . . . . A . | | . . . . . . . . . . A . |
| . . A . . . . . . . . . | | . . A . . . . . . . . . |
| . . . . . . . A . . . . | | . . . . . . . A . . . . |
+-------------------------+ +-------------------------+
CROSSREFS
A051223 = 2*A352661 + 4*A352662 + 8*A352663 (when n>1).
Sequence in context: A337999 A037224 A122670 * A283494 A353254 A281034
KEYWORD
nonn,more
AUTHOR
Don Knuth, Mar 25 2022
STATUS
approved