{List(),List(1,2,3,4,5,6,7,8)}
{List(1,2,3,4),List(5,6,7,8)}
{List(1,2,3,4,5,6,7,8),List()}

{List(),List(8,7,6,5,4,3,2,1)}
{List(4,3,2,1),List(8,7,6,5)}
{List(8,7,6,5,4,3,2,1),List()}

{List(),List(7,2,1,5,4,3,8,6)}
{List(2,1,4,3),List(7,5,8,6)}
{List(7,2,1,5,4,3,8,6),List()}

List(1,2,3,4,5,6,7,8)

{List(),List(1,2,3,4,5,6,7,8)}
{List(1,2,3,4),List(5,6,7,8)}
{List(1,2,3,4,5,6,7,8),List()}

{List(),List(8,7,6,5,4,3,2,1)}
{List(4,3,2,1),List(8,7,6,5)}
{List(8,7,6,5,4,3,2,1),List()}

{List(),List(7,2,1,5,4,3,8,6)}
{List(2,1,4,3),List(7,5,8,6)}
{List(7,2,1,5,4,3,8,6),List()}

List(1,2,3,4,5,6,7,8)

List(List())
List(List(),List(1))
List(List(),List(2),List(1),List(1,2))
List(List(),List(3),List(2),List(2,3),List(1),List(1,3),List(1,2),List(1,2,3))
List(List(),List(4),List(3),List(3,4),List(2),List(2,4),List(2,3),List(2,3,4),List(1),List(1,4),List(1,3),List(1,3,4),List(1,2),List(1,2,4),List(1,2,3),List(1,2,3,4))

queens(1) = List(List({1,1}))
queens(2) = List()
queens(3) = List()
queens(4) = List(List({4,3},{3,1},{2,4},{1,2}),List({4,2},{3,4},{2,1},{1,3}))

queens(1) = List(List(1))
queens(2) = List()
queens(3) = List()
queens(4) = List(List(3,1,4,2),List(2,4,1,3))