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Number of n x n crossword puzzles with rotational symmetry and exactly one black square per row.
4

%I #3 Nov 11 2010 07:34:06

%S 0,0,0,2,2,10,12,120,186

%N Number of n x n crossword puzzles with rotational symmetry and exactly one black square per row.

%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.

%H Marc Brodie, <a href="/A132443/a132443.txt">Mathematica program</a>

%e a(6) = 2 because the only two 6 X 6 crossword puzzles are (using 1's for black squares and 0's for white):

%e 100000

%e 100000

%e 100000

%e 000001

%e 000001

%e 000001

%e and

%e 000001

%e 000001

%e 000001

%e 100000

%e 100000

%e 100000

%Y Cf. A130578, A132444, A132445, A132446.

%K nonn

%O 3,4

%A Marc Brodie (mbrodie(AT)wju.edu), Aug 21 2007