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The number of n X n real {0,1}-matrices the square of which is the all-ones matrix.
1

%I #6 Mar 12 2017 15:11:33

%S 1,0,0,12,0,0,0,0,1330560,0,0,0,0,0,0

%N The number of n X n real {0,1}-matrices the square of which is the all-ones matrix.

%C See A283627 for much more information.

%Y The main entry for this problem is A283627.

%K nonn

%O 1,4

%A _N. J. A. Sloane_, Mar 12 2017