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%I #6 Apr 21 2021 14:18:40
%S 64,8272,322,81456,530,230446
%N Number of (n+1) X (n+1) 0..3 arrays with each 2 X 2 subblock off diagonal and antidiagonal nonsingular and the array of 2 X 2 subblock determinants antisymmetric about the diagonal and antidiagonal.
%C Column 3 of A187705.
%e Some solutions for 4 X 4
%e ..0..0..3..0....0..0..2..0....2..1..0..0....0..0..1..1....0..2..0..0
%e ..2..1..1..0....2..3..2..0....2..1..1..1....3..3..3..3....0..1..1..2
%e ..3..3..3..3....0..3..2..3....3..1..1..0....0..1..1..2....2..1..1..0
%e ..2..2..1..1....0..3..0..0....0..0..1..0....0..3..0..0....0..0..2..0
%Y Cf. A187705.
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 12 2011