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Number of x X n symmetric binary matrices containing no more than three 1s in any 2 X 2 sub-block.
1

%I #8 Mar 09 2015 04:28:20

%S 1,2,7,49,648,16475,801489,74700792,13333992705,4558747755857,

%T 2985167883475040,3743977846899435969,8993695705522239110137,

%U 41379357418095833391759776,364644672948881035681654421967

%N Number of x X n symmetric binary matrices containing no more than three 1s in any 2 X 2 sub-block.

%H R. H. Hardin, May 31 2008, <a href="/A139008/b139008.txt">Table of n, a(n) for n = 0..23</a>

%K nonn

%O 0,2

%A _R. H. Hardin_, May 31 2008