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A127503 Number of n X n matrices A with 1's on the main diagonal and -1's and 0's elsewhere such that A + A' has only 0's and -1's off the main diagonal and is positive semi-definite. 2

%I

%S 1,3,27,281,3945,70635,1437555,30357425,628337745

%N Number of n X n matrices A with 1's on the main diagonal and -1's and 0's elsewhere such that A + A' has only 0's and -1's off the main diagonal and is positive semi-definite.

%C For number of different values of A + A' see A084553.

%Y Cf. A085657, A085658, A080858, A083029, A038379, A127502.

%K nonn,more,nice

%O 1,2

%A _Max Alekseyev_, Jan 16 2007

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Last modified January 26 14:08 EST 2020. Contains 331280 sequences. (Running on oeis4.)