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%I #7 Feb 18 2018 08:40:25
%S 2,5,12,28,66,156,368,868,2048,4832,11400,26896,63456,149712,353216,
%T 833344,1966112,4638656,10944000,25820224,60917760,143723520,
%U 339087488,800010496,1887468032,4453111040,10506243072,24787422208,58481066496
%N Number of n X 1 0..3 arrays with no element equal to one plus the sum of elements to its left or three plus the sum of elements above it, modulo 4.
%C Column 1 of A239340.
%H R. H. Hardin, <a href="/A239333/b239333.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 2*a(n-1) +2*a(n-3).
%F Empirical g.f.: (2 + x + 2*x^2) / (1 - 2*x - 2*x^3). - _Colin Barker_, Feb 18 2018
%e Some solutions for n=5:
%e ..0....2....2....2....0....0....0....0....2....2....2....2....2....0....2....2
%e ..2....0....2....0....2....0....2....0....0....0....0....2....2....2....0....3
%e ..2....2....2....3....2....2....3....0....2....2....3....0....0....0....3....2
%e ..0....0....0....2....2....2....2....0....2....2....3....0....2....0....2....3
%e ..2....2....2....0....2....0....0....0....3....0....2....2....3....2....3....2
%K nonn
%O 1,1
%A _R. H. Hardin_, Mar 16 2014
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