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%I #9 Oct 19 2018 08:08:25
%S 100,688,4524,30624,203804,1370656,9159084,61448672,411235964,
%T 2756437664,18457746444,123673955168,828338389340,5549386326048,
%U 37171828238188,249015367157984,1668057104261948,11174114559613344,74852144107435468
%N Number of (n+1) X (1+1) 0..3 arrays with the upper median equal to the lower median in every 2 X 2 subblock.
%H R. H. Hardin, <a href="/A235850/b235850.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) + 37*a(n-2) - 10*a(n-3) - 200*a(n-4) + 128*a(n-5).
%F Empirical g.f.: 4*x*(25 + 122*x - 138*x^2 - 720*x^3 + 512*x^4) / (1 - 2*x - 37*x^2 + 10*x^3 + 200*x^4 - 128*x^5). - _Colin Barker_, Oct 19 2018
%e Some solutions for n=4:
%e ..1..1....1..1....2..2....3..1....1..2....0..1....0..1....0..2....0..2....3..0
%e ..1..1....3..1....2..1....2..2....2..2....1..3....0..0....0..0....0..0....1..1
%e ..3..1....1..1....1..0....1..3....1..3....1..1....0..1....0..1....0..2....3..1
%e ..1..1....1..3....1..1....2..2....3..3....0..1....1..1....2..1....0..0....3..3
%e ..2..1....0..1....3..1....1..2....0..3....1..3....2..1....2..3....1..0....3..1
%Y Column 1 of A235856.
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 16 2014
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