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%I #6 Dec 18 2015 18:17:39
%S 1,1,3,15,115,1587,33283,1147868,64664807,5886944926,868821662115,
%T 207892029761070,80727613405529244,50826500691456029359,
%U 51893686154530928512158,85927150265759233982684320
%N Half the number of n X n symmetric binary matrices with no element equal to a strict majority of its vertical, antidiagonal and horizontal neighbors
%H R. H. Hardin, <a href="/A190629/b190629.txt">Table of n, a(n) for n = 1..20</a>
%e Some solutions for n=4 with a(1,1)=0
%e ..0..1..0..1....0..1..0..1....0..1..0..0....0..1..0..0....0..1..0..1
%e ..1..1..0..0....1..0..1..0....1..0..1..1....1..0..1..1....1..1..0..1
%e ..0..0..1..1....0..1..0..1....0..1..0..1....0..1..0..0....0..0..1..0
%e ..1..0..1..0....1..0..1..0....0..1..1..0....0..1..0..1....1..1..0..1
%K nonn
%O 1,3
%A _R. H. Hardin_ May 14 2011
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