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%I #6 Dec 18 2015 18:17:44
%S 4,10,42,248,2290,31042,641376,19753266,918924546,64065187024,
%T 6724991990090,1059952700132050,251257954485037072,
%U 89488725743024413554,47916300899545924260762,38558096411377540692559456
%N Number of lower triangles of an n X n 0..3 array with each element differing from all of its horizontal and vertical neighbors by one
%C Column 3 of A194998
%H R. H. Hardin, <a href="/A194993/b194993.txt">Table of n, a(n) for n = 1..32</a>
%e Some solutions for 4X4
%e ..1........3........2........3........1........2........1........3
%e ..2.3......2.1......1.2......2.1......0.1......3.2......2.1......2.3
%e ..1.2.3....1.2.3....2.1.2....3.2.3....1.2.3....2.1.2....1.2.1....3.2.1
%e ..0.1.2.3..0.1.2.3..3.2.3.2..2.3.2.3..2.3.2.1..3.2.1.2..2.1.2.3..2.1.0.1
%K nonn
%O 1,1
%A _R. H. Hardin_ Sep 07 2011
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