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A201956 Number of zero-sum nX3 -3..3 arrays with every element unequal to at most two horizontal and vertical neighbors.

%I A201956 #7 Jul 22 2025 16:24:40
%S A201956 37,1587,17091,303955,4735345,85454789,1489376611,27222524599,
%T A201956 493561989579,9124430335331,168519041238653,3142665027511853,
%U A201956 58661584782394781,1101133968614654601,20697996312691430763
%N A201956 Number of zero-sum nX3 -3..3 arrays with every element unequal to at most two horizontal and vertical neighbors.
%C A201956 Column 3 of A201958
%H A201956 R. H. Hardin, <a href="/A201956/b201956.txt">Table of n, a(n) for n = 1..20</a>
%e A201956 Some solutions for n=3
%e A201956 ..1.-2.-2....2..2..2....1..0..1...-1..1..1....2..3..3....2..2.-1....0.-2..3
%e A201956 ..1..1.-2....0..0..0...-2..0..1...-1..2..2...-3.-3..3....2..0..0....1.-2..3
%e A201956 .-1..1..3....0.-3.-3...-2..0..1...-3..2.-3...-1.-3.-1...-2..0.-3....1.-2.-2
%K A201956 nonn
%O A201956 1,1
%A A201956 _R. H. Hardin_ Dec 06 2011