%I M1997 N0788
%S 0,1,2,11,32,50,132,380,368,1135,1120,4348,3622,10568,30634,46304,
%T 55576,152210
%N No3inline problem on n X n grid: total number of ways of placing 2n points on n X n grid so no 3 are in a line. No symmetries are taken into account.
%C This means no three on any line, not just lines in the X or Y directions.
%D M. A. Adena, D. A. Holton and P. A. Kelly, Some thoughts on the nothreeinline problem, pp. 617 of Combinatorial Mathematics (Proceedings 2nd Australian Conf.), Lect. Notes Math. 403, 1974.
%D R. K. Guy, Unsolved combinatorial problems, pp. 121127 of D. J. A. Welsh, editor, Combinatorial Mathematics and Its Applications. Academic Press, NY, 1971.
%D R. K. Guy and P. A. Kelly, The NoThreeLine Problem. Research Paper 33, Department of Mathematics, Univ. of Calgary, Calgary, Alberta, 1968. Condensed version in Canad. Math. Bull. Vol. 11, pp. 527531, 1968.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Benjamin Chaffin, <a href="http://wso.williams.edu/~bchaffin/no_three_in_line/index.htm">NoThreeInLine Problem</a>.
%H A. Flammenkamp, <a href="http://wwwhomes.unibielefeld.de/achim/no3in/readme.html">Progress in the nothreeinline problem</a>
%H A. Flammenkamp, <a href="http://wwwhomes.unibielefeld.de/achim/no3in/table_old.txt">Solutions of the nothreeinline problem</a>
%H A. Flammenkamp, <a href="http://wwwhomes.unibielefeld.de/achim/no3in/table.txt">Solutions of the nothreeinline problem</a>
%H M. Gardner, R. L. Graham, M. Meierruth, R. Jacobson, <a href="/A000755/a000755_3.pdf">Correspondence, 1976</a>
%H R. K. Guy and P. A. Kelly, <a href="/A000755/a000755_1.pdf">The NoThreeLine Problem</a>, Research Paper 33, Department of Mathematics, Univ. of Calgary, Calgary, Alberta, 1968. [Annotated scanned copy]
%H R. K. Guy and P. A. Kelly, <a href="/A000755/a000755_2.pdf">The NoThreeLine Problem</a>, condensed version in Canad. Math. Bull. Vol. 11, pp. 527531, 1968. [Annotated scanned copy]
%H R. K. Guy, P. A. Kelly, N. J. A. Sloane, <a href="/A000755/a000755.pdf">Correspondence, 19681971</a>
%e a(3) = 2:
%e X X o ... o X X
%e X o X ... X o X
%e o X X ... X X o
%Y Cf. A000769 (inequivalent solutions).
%K nonn,nice
%O 1,3
%A _N. J. A. Sloane_
%E More terms from the _Achim Flammenkamp_ web site, May 24 2005
%E a(17) and a(18) from _Benjamin Chaffin_, Apr 05 2006
%E Minor edits from _N. J. A. Sloane_, May 25 2010
