

A051757


Consider problem of placing A051754(n) queens on an n X n board so that each queen attacks precisely 1 other. Sequence gives number of solutions up to square symmetry.


2




OFFSET

2,1


COMMENTS

When n is a multiple of 3, the bound of 2[2n/3] queens is so tight that in solutions with that number of queens, all attacks must be along rows or columns, making solutions rare.  Jud McCranie


REFERENCES

Martin Gardner, The Last Recreations, Copernicus, 1997, 274283.


LINKS



CROSSREFS



KEYWORD

nonn,nice


AUTHOR

Robert Trent (trentrd(AT)hotmail.com), Aug 23 2000


EXTENSIONS



STATUS

approved



