%I A032522 M0330 N0125
%S A032522 1,0,0,2,2,4,8,4,16,12,48,80,136,420,1240,3000,8152,18104,44184,144620,
%T A032522 375664,1250692,3581240,11675080,34132592,115718268,320403024,
%U A032522 1250901440,3600075088,14589438024,43266334696,181254386312
%N A032522 Number of symmetric solutions to non-attacking queens problem on n X 
               n board.
%D A032522 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A032522 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A032522 R. J. Walker, An enumerative technique for a class of combinatorial problems, 
               pp. 91-94 of Proc. Sympos. Applied Math., vol. 10, Amer. Math. Soc., 
               1960.
%H A032522 W. Schubert, <a href="b032522.txt">Table of n, a(n) for n = 1..36</a>
%H A032522 M. Szabo, <a href="http://www.nexus.hu/mikk/queen/index.html">Non-attacking 
               Queens Problem Page</a>
%H A032522 W. Schubert, <a href="http://m29s20.vlinux.de/~wschub/nqueen.html">N-Queens 
               page</a>
%Y A032522 Cf. A002562, A033148, A037224, A037223.
%Y A032522 Sequence in context: A116694 A137778 A000017 this_sequence A077964 A077968 
               A123958
%Y A032522 Adjacent sequences: A032519 A032520 A032521 this_sequence A032523 A032524 
               A032525
%K A032522 nonn,nice,hard
%O A032522 1,4
%A A032522 Miklos SZABO (mike(AT)ludens.elte.hu)
%E A032522 More terms for n = 33..36 from W. Schubert (wschubnq(AT)gmx.de), Jul 
               31 2009