%I A002564 M3199 N1293
%S A002564 1,4,1,12,186,4,86,4860
%N A002564 Queens problem.
%D A002564 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A002564 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002564 M. A. Sainte-Lagu\"{e}, Les R\'{e}seaux (ou Graphes)}, M\'{e}morial des 
               Sciences Math\'{e}matiques, Fasc. 18, Gauthier-Villars, Paris, 1926, 
               p. 49.
%Y A002564 Sequence in context: A019238 A157404 A135704 this_sequence A019428 A055252 
               A116414
%Y A002564 Adjacent sequences: A002561 A002562 A002563 this_sequence A002565 A002566 
               A002567
%K A002564 nonn
%O A002564 1,2
%A A002564 N. J. A. Sloane (njas(AT)research.att.com).