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%I #16 Nov 27 2018 09:01:07
%S 38,110,322,966,2930,8982,27714,85958,267602,835574,2615266,8202150,
%T 25769714,81093846,255569538,806554502,2548769426,8064427958,
%U 25546995490,81022985574,257251995698,817658450070,2601529209282,8285338752326
%N Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock summing to 6 and no 2 X 2 subblock having exactly two nonzero entries.
%H R. H. Hardin, <a href="/A251229/b251229.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 7*a(n-1) - 12*a(n-2) - 8*a(n-3) + 24*a(n-4).
%F Empirical g.f.: 2*x*(19 - 78*x + 4*x^2 + 168*x^3) / ((1 - 2*x)*(1 - 3*x)*(1 - 2*x - 4*x^2)). - _Colin Barker_, Nov 27 2018
%e Some solutions for n=4:
%e ..2..1....1..2....1..3....2..1....2..1....0..2....2..1....3..1....3..2....1..1
%e ..3..0....3..0....1..1....1..2....1..2....1..3....3..0....0..2....1..0....2..2
%e ..2..1....1..2....2..2....2..1....0..3....2..0....1..2....1..3....3..2....0..2
%e ..1..2....1..2....1..1....2..1....1..2....3..1....0..3....1..1....0..1....3..1
%e ..2..1....3..0....1..3....3..0....0..3....0..2....2..1....1..3....2..3....1..1
%Y Column 1 of A251236.
%K nonn
%O 1,1
%A _R. H. Hardin_, Nov 30 2014
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