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A239820 Number of 2Xn 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it, modulo 4.

%I A239820 #6 Jun 02 2025 09:32:34
%S A239820 5,23,132,729,3951,21602,118253,646306,3532732,19315270,105601487,
%T A239820 577330665,3156353205,17256335056,94343160597,515789128277,
%U A239820 2819903064231,15416868881838,84286524854294,460808121256380,2519312876415017
%N A239820 Number of 2Xn 0..3 arrays with no element equal to zero plus the sum of elements to its left or one plus the sum of the elements above it, modulo 4.
%C A239820 Row 2 of A239819
%H A239820 R. H. Hardin, <a href="/A239820/b239820.txt">Table of n, a(n) for n = 1..210</a>
%F A239820 Empirical: a(n) = 9*a(n-1) -28*a(n-2) +74*a(n-3) -181*a(n-4) +236*a(n-5) -261*a(n-6) +234*a(n-7) +200*a(n-8) -279*a(n-9) +104*a(n-10) -268*a(n-11) -36*a(n-12) +156*a(n-13) +104*a(n-14) -32*a(n-15) -16*a(n-16)
%e A239820 Some solutions for n=5
%e A239820 ..3..0..0..0..0....3..2..3..2..3....3..0..0..2..3....3..0..2..0..2
%e A239820 ..2..0..3..0..3....2..0..1..2..2....2..3..2..0..1....1..0..2..0..1
%K A239820 nonn
%O A239820 1,1
%A A239820 _R. H. Hardin_, Mar 27 2014