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Number of n X 3 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or vertically.
1

%I #6 Oct 02 2021 10:25:38

%S 7,145,2411,39321,647287,10652849,175284259,2884208601,47458332799,

%T 780904692697,12849420860335,211431203704621,3479001459520535,

%U 57245340037605157,941945266264605543,15499268308326369925

%N Number of n X 3 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or vertically.

%C Column 3 of A232368.

%H R. H. Hardin, <a href="/A232363/b232363.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 15*a(n-1) +13*a(n-2) +171*a(n-3) +144*a(n-4) +128*a(n-5) -1072*a(n-6) -5144*a(n-7) -6575*a(n-8) -1670*a(n-9) +29979*a(n-10) +28328*a(n-11) -17313*a(n-12) -16033*a(n-13) -7412*a(n-14) -6950*a(n-15) +6052*a(n-16) +6881*a(n-17) +4681*a(n-18) +3057*a(n-19) +575*a(n-20) +420*a(n-21).

%e Some solutions for n=4

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

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

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

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

%Y Cf. A232368.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 23 2013