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Number of nXnXn triangular 0..2 arrays with some element plus some adjacent element totalling 2 exactly once.
1

%I #5 Mar 14 2016 09:14:22

%S 0,12,66,468,3612,40020,601368,12473568,355574028,13968754800,

%T 756926837340,56646343727400,5861182843734528,839281074844449036,

%U 166460255072308752300,45762947464712474066844

%N Number of nXnXn triangular 0..2 arrays with some element plus some adjacent element totalling 2 exactly once.

%C Column 2 of A270256.

%H R. H. Hardin, <a href="/A270251/b270251.txt">Table of n, a(n) for n = 1..24</a>

%e Some solutions for n=4

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

%e ....2.1......2.1......2.2......0.0......1.0......2.1......1.0......2.1

%e ...2.1.2....1.2.2....1.2.2....0.0.0....1.0.1....2.1.2....0.0.1....2.2.2

%e ..2.2.2.1..1.2.1.2..0.2.2.1..0.1.1.0..0.0.0.0..2.2.2.2..1.0.1.2..1.1.2.2

%Y Cf. A270256.

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 14 2016