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A140884 Half the number of n X n binary matrices, symmetric under 90-degree rotation, having equal row sums. 0

%I

%S 1,1,1,4,3,13,43,580,1897,23851,149041,14348161,74552521,7849966951,

%T 311500453881,64690704744716,2466747100788601,493809829542170401

%N Half the number of n X n binary matrices, symmetric under 90-degree rotation, having equal row sums.

%K nonn

%O 1,4

%A _R. H. Hardin_, Jul 28 2008

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Last modified July 6 04:31 EDT 2022. Contains 355108 sequences. (Running on oeis4.)