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%I #8 Oct 06 2018 06:15:20
%S 6,12,26,56,120,258,554,1190,2556,5490,11792,25328,54402,116850,
%T 250982,539084,1157898,2487048,5341928,11473922,24644826,52934598,
%U 113698172,244212194,524543136,1126665696,2419964162,5197838690,11164432710
%N Number of n X 2 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally, vertically or antidiagonally.
%H R. H. Hardin, <a href="/A232935/b232935.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = a(n-1) + 2*a(n-2) + a(n-3).
%F Empirical g.f.: 2*x*(3 + 3*x + x^2) / (1 - x - 2*x^2 - x^3). - _Colin Barker_, Oct 06 2018
%e Some solutions for n=5:
%e ..2..1....0..0....0..1....0..0....1..2....0..1....1..0....2..2....0..1....0..0
%e ..2..2....0..1....0..0....0..1....2..1....0..0....0..1....2..2....0..0....1..0
%e ..1..2....0..0....0..1....0..0....2..2....1..0....0..0....2..1....1..0....0..0
%e ..2..1....0..0....0..0....1..0....2..2....0..0....1..0....2..2....0..1....0..0
%e ..2..2....0..1....1..0....0..1....2..1....0..1....0..1....2..2....0..0....0..0
%Y Column 2 of A232941.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 02 2013