A019318 ?

[Jim Nastos]

SeqFans,
  Sequence A019318 is named "Ways of placing n queens on an n X n board."
  (Full sequence description appended below)

  If one assumes this means *non-attacking* queens, then there should be 
no solution for n = 2 or 3 ... but the sequence has values 2 and 16 for 
these values.

  If we don't specify the non-attacking property, why mention queens?

  If we assume it is just talking about placement of N 1's on an NxN 
square, N=2 should have 4 placements, unless it is counting nonisomorphic 
positions. (with respect to rotations and reversals and such) 

  If we assume nonisomorphic configurations, I don't see N=3 being 16.

  Can anyone find any consistent interpretation of this?

Jim

ID Number: A019318
Sequence:  1,2,16,252,6814,244344,10746377,553319048,32611596056,
           2163792255680
Name:      Ways of placing n queens on an n X n board.
Links:     Source
Keywords:  nonn
Offset:    1
Author(s): Mario Velucchi (mathchess(AT)velucchi.it)