A352661 Number of doubly symmetric characteristic solutions to the n-superqueens problem.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0, 12, 17, 0, 0, 60, 82

Offset: 1

Author

Don Knuth, Mar 25 2022

Keywords

• nonn
• more

Comments

Superqueens are also called amazons. They combine the moves of queen and knight.

Examples

			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 . . . . |
  +-------------------------+ +-------------------------+
		

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).

Crossrefs

A051224 = A352661 + A352662 + A352663.

A051223 = 2*A352661 + 4*A352662 + 8*A352663 (when n>1).