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%I #6 Dec 18 2015 18:17:40
%S 2,8,62,966,29888,1838552,224969616,54745613520,26495136860880,
%T 25502057625872912,48817512227401500592,185852155121293444267024,
%U 1407184656492293192061559200,21189763355834331020518358995456
%N Number of n X n symmetric binary matrices with each 1 adjacent to no more than 5 horizontally, vertically or diagonally neighboring 1s
%H R. H. Hardin, <a href="/A191604/b191604.txt">Table of n, a(n) for n = 1..21</a>
%e Some solutions for n=4
%e ..0..0..1..1....1..1..1..1....1..1..1..1....1..0..0..0....1..0..1..1
%e ..0..1..0..1....1..1..1..0....1..0..1..1....0..1..1..1....0..0..1..1
%e ..1..0..0..0....1..1..0..1....1..1..1..0....0..1..0..1....1..1..0..0
%e ..1..1..0..1....1..0..1..0....1..1..0..1....0..1..1..1....1..1..0..1
%K nonn
%O 1,1
%A _R. H. Hardin_ Jun 08 2011
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