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%I #15 Dec 22 2019 19:10:18
%S 3,120,2530,58458,1317540,30132444,684657326,15594228288,354894362166,
%T 8078976180614,183894888689408,4185999926427220,95284617951103300,
%U 2168945067666040200,49371181800142293644,1123825227937533564738
%N 1/3 the number of n X 4 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.
%C Column 4 of A185559
%H R. H. Hardin, <a href="/A185554/b185554.txt">Table of n, a(n) for n = 1..200</a>
%H Robert Israel, <a href="/A185554/a185554.txt">Linear recurrence of order 101</a>
%H Robert Israel, <a href="/A185554/a185554.pdf">Maple-assisted derivation of recurrence</a>
%F Linear recurrence of order 101: see link. - _Robert Israel_, Dec 22 2019
%e Some solutions for 6 X 4 with a(1,1)=0:
%e 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1
%e 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
%e 2 1 0 0 0 1 2 2 0 1 0 0 2 1 0 2 1 1 2 2
%e 2 1 2 2 0 2 1 2 0 2 2 1 2 1 2 2 2 0 1 1
%e 0 0 0 2 2 2 1 1 0 0 2 1 0 1 1 1 2 0 1 2
%e 1 1 1 2 0 0 0 1 1 1 1 1 0 0 2 2 0 0 1 2
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 31 2011
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