%I #2 Feb 27 2009 03:00:00
%S 0,0,0,1,1,5,6,60,93
%N Number of n x n crossword puzzles with rotational symmetry and exactly one black square per row, up to symmetry.
%C Acceptable crossword puzzles must have all words of length 3 or more, at least one word in each row and each column and be connected. Since the puzzles counted in sequence A132443 come naturally in pairs (by reflective symmetry), the numbers in this sequence are obtained by dividing the corresponding numbers in A132443 by 2.
%e a(6) = 1 because up to symmetry, the only 6 X 6 crossword puzzle with exactly one black square in each row (using 1's for black squares and 0's for white) is:
%e 100000
%e 100000
%e 100000
%e 000001
%e 000001
%e 000001
%p See the program for A132443
%Y Cf. A130578, A132443, A132445, A132446.
%K nonn
%O 3,6
%A Marc Brodie (mbrodie(AT)wju.edu), Aug 21 2007
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