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A199643 Number of nX4 0..2 arrays with values 0..2 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.

%I A199643 #7 Jul 22 2025 13:20:59
%S A199643 2,60,1265,29229,658770,15066222,342328663,7797114144,177447181083,
%T A199643 4039488090307,91947444344704,2092999963213610,47642308975551650,
%U A199643 1084472533833020100,24685590900071146822,561912613968766782369
%N A199643 Number of nX4 0..2 arrays with values 0..2 introduced in row major order and each element equal to one or two horizontal and vertical neighbors.
%C A199643 Column 4 of A199647
%H A199643 R. H. Hardin, <a href="/A199643/b199643.txt">Table of n, a(n) for n = 1..200</a>
%e A199643 Some solutions for n=3
%e A199643 ..0..1..1..2....0..1..1..0....0..0..0..0....0..0..1..1....0..0..0..1
%e A199643 ..0..1..1..2....0..1..2..0....0..1..1..1....2..2..2..1....1..2..2..1
%e A199643 ..2..2..2..2....0..0..2..2....2..2..2..2....2..1..1..1....1..1..1..1
%K A199643 nonn
%O A199643 1,1
%A A199643 _R. H. Hardin_ Nov 08 2011