A191481 - OEIS

%I #6 Dec 18 2015 18:17:39

%S 2,8,57,810,22619,1219719,127845270,26032342551,10293291175885,

%T 7905921432890001,11794027077033857745,34172420487154828030022,

%U 192310322681418948575293174,2102041102462630258932750207474

%N Number of n X n symmetric binary matrices with each 1 adjacent to no more than 5 king-move neighboring 1s

%H R. H. Hardin, <a href="/A191481/b191481.txt">Table of n, a(n) for n = 1..16</a>

%e Some solutions for n=4

%e ..1..0..0..0....1..1..1..1....0..0..0..1....0..1..0..0....1..0..1..1

%e ..0..0..0..0....1..0..1..0....0..1..0..1....1..0..0..1....0..0..0..1

%e ..0..0..1..1....1..1..0..1....0..0..1..1....0..0..0..1....1..0..0..0

%e ..0..0..1..0....1..0..1..0....1..1..1..0....0..1..1..0....1..1..0..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Jun 03 2011