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.

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.

Terms

    a(0) =2a(1) =7a(2) =5a(3) =93a(4) =2a(5) =149a(6) =49a(7) =1a(8) =12897a(9) =2238a(10) =109a(11) =2606412a(12) =450118a(13) =17579

External references