login
Number of n X 3 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.
1

%I #6 Apr 21 2021 14:27:08

%S 0,6,34,208,1272,7818,47998,294832,1810916,11123242,68322370,

%T 419657160,2577663664,15832804586,97249963694,597339237368,

%U 3669041620356,22536383966338,138425413185266,850251533001856,5222506855786032

%N Number of n X 3 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.

%C Column 3 of A231063.

%H R. H. Hardin, <a href="/A231058/b231058.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 8*a(n-1) -9*a(n-2) -20*a(n-3) +29*a(n-4) +22*a(n-5) -23*a(n-6) -14*a(n-7) -14*a(n-8) +4*a(n-9) +2*a(n-10).

%e Some solutions for n=4

%e ..0..3..0....0..3..2....0..1..2....0..3..2....0..3..2....0..1..2....0..3..2

%e ..1..2..1....1..2..1....1..0..3....1..2..1....1..2..1....3..0..3....1..0..3

%e ..2..3..0....0..1..0....2..3..2....2..1..0....0..3..0....2..1..0....2..3..2

%e ..1..2..3....3..0..3....1..0..1....3..0..3....3..2..1....3..0..3....1..2..1

%Y Cf. A231063.

%K nonn

%O 1,2

%A _R. H. Hardin_, Nov 03 2013