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Number of lower triangles of an n X n 0..7 array with each element differing from all of its horizontal and vertical neighbors by one
1

%I #6 Dec 18 2015 18:17:45

%S 8,26,138,1104,13754,261324,7686580,346018484,24069199390,

%T 2566345975600,422456182660436,106689940668487188,

%U 41576384767924321080,24871115264481653525780,22948996533081051784100632

%N Number of lower triangles of an n X n 0..7 array with each element differing from all of its horizontal and vertical neighbors by one

%C Column 7 of A194998

%H R. H. Hardin, <a href="/A194997/b194997.txt">Table of n, a(n) for n = 1..22</a>

%e Some solutions for 4X4

%e ..2........6........2........2........2........0........2........2

%e ..3.2......7.6......3.4......3.2......3.2......1.0......3.2......1.2

%e ..2.1.0....6.5.6....2.3.2....2.1.0....2.3.2....2.1.0....2.3.2....2.3.2

%e ..1.0.1.0..5.6.7.6..3.4.3.2..1.2.1.0..1.2.1.0..1.2.1.0..3.4.3.2..3.4.3.4

%K nonn

%O 1,1

%A _R. H. Hardin_ Sep 07 2011