cp's OEIS Frontend

A232155 Number of n X 2 0..3 arrays with every 0 next to a 1, every 1 next to a 2 and every 2 next to a 3 horizontally, vertically or antidiagonally, and no adjacent values equal.

%I A232155 #7 Oct 03 2018 10:50:05
%S A232155 2,18,62,218,746,2600,9004,31262,108492,376566,1307146,4537292,
%T A232155 15750222,54673186,189786782,658806476,2286917482,7938591212,
%U A232155 27557292770,95659868830,332064969492,1152700237642,4001379292082,13890026339060
%N A232155 Number of n X 2 0..3 arrays with every 0 next to a 1, every 1 next to a 2 and every 2 next to a 3 horizontally, vertically or antidiagonally, and no adjacent values equal.
%H A232155 R. H. Hardin, <a href="/A232155/b232155.txt">Table of n, a(n) for n = 1..210</a>
%F A232155 Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - 13*a(n-3) - 5*a(n-4) + 14*a(n-5) - 3*a(n-6) + 3*a(n-7) + 8*a(n-8) + a(n-9) - a(n-10) for n>11.
%F A232155 Empirical g.f.: 2*x*(1 + 5*x - 7*x^2 - 20*x^3 - 3*x^4 + 24*x^5 + 5*x^6 + 7*x^7 + 15*x^8 + 2*x^9 - 2*x^10) / (1 - 4*x - 2*x^2 + 13*x^3 + 5*x^4 - 14*x^5 + 3*x^6 - 3*x^7 - 8*x^8 - x^9 + x^10). - _Colin Barker_, Oct 03 2018
%e A232155 Some solutions for n=7:
%e A232155 ..2..1....2..3....3..1....0..3....1..3....0..1....0..1....2..1....3..0....1..2
%e A232155 ..3..0....0..1....0..2....1..2....2..1....2..3....3..2....3..2....1..3....0..3
%e A232155 ..2..3....2..3....3..1....3..0....3..0....1..2....0..1....1..0....2..0....1..0
%e A232155 ..1..2....0..1....2..0....2..1....1..2....0..3....3..2....3..2....1..3....2..1
%e A232155 ..3..1....2..3....3..1....3..2....3..1....1..0....1..3....0..1....2..1....3..0
%e A232155 ..2..0....1..2....0..2....1..0....2..3....2..3....2..1....3..2....3..0....1..2
%e A232155 ..3..2....0..3....1..3....2..3....1..0....1..2....3..2....0..1....2..1....3..1
%Y A232155 Column 2 of A232161.
%K A232155 nonn
%O A232155 1,1
%A A232155 _R. H. Hardin_, Nov 19 2013