%I #5 Mar 31 2012 12:36:09
%S 24,550,4044,17716,56080,150166,336776,702408,1330728,2385910,3973400,
%T 6550700,10068336,15247986,22545648,32579360,45246528,62983046,
%U 84524916,113900920,150370548,195521534,249456396,321513812,404142192,504603526
%N Number of 3X3 0..n arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal
%C Row 2 of A187670
%H R. H. Hardin, <a href="/A187671/b187671.txt">Table of n, a(n) for n = 1..31</a>
%e Some n=3 solutions for 3X3
%e ..3..3..3....2..1..3....0..1..0....2..1..1....1..0..3....3..0..2....2..3..1
%e ..0..1..0....2..0..2....2..1..2....2..2..0....0..3..2....0..1..2....1..0..1
%e ..3..0..3....0..1..0....2..2..2....2..1..1....3..3..3....2..0..3....2..3..2
%K nonn
%O 1,1
%A _R. H. Hardin_ Mar 12 2011