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%I #20 Mar 30 2012 17:28:27
%S 3,9,29,93,279
%N Minimum number of squares removed from an n-dimensional tic-tac-toe board to make winning impossible for either player.
%C A156989 is the main sequence for this entry. Related to the density Hales-Jewett theorem.
%H Steve Landsburg, <a href="http://www.thebigquestions.com/2010/04/08/blogging-tic-tac-toe-and-the-future-of-math/">Blogging, Tic Tac Toe and the Future of Math</a>
%F a(n) = 3^n - A156989(n).
%Y Cf. A156989.
%K nonn,hard
%O 2,1
%A _Charles R Greathouse IV_, Sep 26 2011