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Number of lower triangles of an n X n 0..3 array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by two or less
1

%I #7 Dec 18 2015 18:17:45

%S 4,46,1682,190514,67379894,74236765958,254948725307650,

%T 2728873272983950594,91038149737139587502854,

%U 9466106148769015848820814134,3067809430979519600024270636572850

%N Number of lower triangles of an n X n 0..3 array with each element differing from all of its diagonal, vertical, antidiagonal and horizontal neighbors by two or less

%C Column 3 of A195248

%H R. H. Hardin, <a href="/A195243/b195243.txt">Table of n, a(n) for n = 1..18</a>

%e Some solutions for n=5

%e ..1..........2..........1..........3..........0..........1..........0

%e ..0.2........2.1........0.2........1.1........2.1........1.3........2.1

%e ..2.0.2......2.0.0......2.1.3......1.1.2......0.2.2......3.3.1......0.2.2

%e ..0.0.1.3....2.1.1.2....0.2.1.3....3.2.1.1....2.1.1.0....3.1.1.3....2.1.1.0

%e ..0.1.2.3.3..1.2.2.1.0..2.1.3.3.3..2.1.2.2.3..1.0.0.1.2..2.3.2.2.1..1.0.0.1.2

%K nonn

%O 1,1

%A _R. H. Hardin_ Sep 13 2011