A051757 - OEIS

%I #8 Mar 30 2012 18:34:54

%S 2,7,5,93,2,149,49,1,12897,2238

%N 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.

%C 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

%D Martin Gardner, The Last Recreations, Copernicus, 1997, 274-283.

%Y Cf. A051754-A051759, A051567-A051571, A019654.

%K nonn,nice

%O 2,1

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

%E More terms from _Jud McCranie_, Aug 14 2001