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%I #5 Mar 31 2012 12:36:20
%S 1,4,28,312,5496,158444,7386598,558062828,68366493762,13583953615958,
%T 4377011029211530,2287186005680108048,1938220889714632813912,
%U 2663689661329760406050654
%N Half the number of nXnXn triangular binary arrays with every element equal to at most 3 neighbors
%e Some solutions for 6X6X6 with a(1,1)=0
%e .......0............0............0............0............0............0
%e ......0.0..........0.0..........0.0..........0.1..........0.0..........0.1
%e .....0.1.0........1.0.1........1.1.1........1.1.1........1.0.1........0.1.1
%e ....1.0.1.1......1.0.1.0......0.1.0.1......0.0.0.0......0.0.1.0......1.0.1.0
%e ...1.1.0.0.1....1.1.0.1.1....1.0.0.1.0....1.0.1.1.0....1.0.1.1.1....0.0.1.0.1
%e ..0.0.1.1.0.0..0.0.0.0.1.0..0.1.1.1.0.0..1.0.1.1.0.1..1.1.1.0.0.1..0.1.1.0.0.0
%K nonn
%O 1,2
%A _R. H. Hardin_ Jul 02 2011
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