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%I #6 Mar 31 2012 12:35:07
%S 1,2,15,417,42176,15701273,21418970801,107224417436160,
%T 1968910887183791359,132633131268024896655873,
%U 32775983842712963307230834176,29712661745725058784174163778464369
%N Number of n X n binary matrices containing no 2 X 2 all-1s sub-block.
%H R. H. Hardin, <a href="/A139810/b139810.txt">Table of n, a(n) for n = 0..19</a>
%K nonn
%O 0,2
%A _R. H. Hardin_, May 23 2008