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%I #9 Apr 04 2018 10:48:25
%S 31,216,1500,10428,72468,503676,3500532,24329052,169088148,1175174460,
%T 8167536180,56764911132,394519788756,2741938101756,19056647102580,
%U 132444930680028,920500836944148,6397540377615036,44463319555825332
%N Half the number of (n+1) X 2 0..2 arrays with no 2 X 2 subblock having sum 4.
%C Column 1 of A183792.
%H R. H. Hardin, <a href="/A183784/b183784.txt">Table of n, a(n) for n = 1..200</a>
%F Empirical: a(n) = 3*a(n-1) + 24*a(n-2) + 24*a(n-3).
%F Empirical g.f.: x*(31 + 123*x + 108*x^2) / (1 - 3*x - 24*x^2 - 24*x^3). - _Colin Barker_, Apr 04 2018
%e Some solutions for 3 X 2:
%e ..1..0....0..1....2..1....0..0....1..0....1..2....1..2....1..2....2..1....0..1
%e ..1..1....0..2....2..2....2..1....2..2....0..2....2..0....2..2....0..2....2..0
%e ..0..1....2..1....1..1....1..2....2..2....0..0....2..2....1..2....1..2....0..1
%Y Cf. A183792.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 07 2011
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