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%I #9 Nov 28 2018 08:04:13
%S 444,3140,22536,164480,1221748,9240612,71163896,557726448,4443661924,
%T 35942893556,294664492808,2444172105248,20477585643732,
%U 173008660351172,1471862511047192,12592888549938000,108236211006760772
%N Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to 3 6 or 9.
%H R. H. Hardin, <a href="/A251294/b251294.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 27*a(n-1) - 260*a(n-2) + 970*a(n-3) - 405*a(n-4) - 3449*a(n-5) - 722*a(n-6) + 840*a(n-7).
%F Empirical g.f.: 4*x*(111 - 2212*x + 13299*x^2 - 14568*x^3 - 56458*x^4 - 9662*x^5 + 13440*x^6) / ((1 - 6*x)*(1 - 7*x)*(1 - 6*x - 5*x^2)*(1 - 8*x - 7*x^2 + 4*x^3)). - _Colin Barker_, Nov 28 2018
%e Some solutions for n=4:
%e ..2..3..0....0..3..3....0..3..3....0..0..2....0..1..0....2..3..1....0..3..2
%e ..1..3..3....0..3..0....3..0..0....0..3..1....0..2..3....2..2..0....0..0..1
%e ..3..2..1....0..0..0....1..2..1....1..2..3....1..3..1....2..3..1....1..2..3
%e ..1..3..0....2..1..2....3..0..0....3..3..1....0..2..0....2..2..3....0..3..1
%e ..1..1..2....0..3..0....0..0..3....3..0..2....2..2..2....1..1..3....1..2..3
%Y Column 2 of A251300.
%K nonn
%O 1,1
%A _R. H. Hardin_, Dec 01 2014
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