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%I #6 Mar 09 2015 00:18:00
%S 1,2,3,29,176,5621,122557,14694960,1181467639,516777127561,
%T 152237306877120,244601068560037129,264412894413046723521,
%U 1557984885076079288613088,6177872087977594821120364739
%N Number of n X n binary matrices, symmetric under 180 degree rotation, with no more than 3 ones in any 2 X 2 subblock.
%H R. H. Hardin, <a href="/A141514/b141514.txt">Table of n, a(n) for n = 0..20</a>
%K nonn
%O 0,2
%A _R. H. Hardin_, Aug 10 2008