|
%I #8 Mar 17 2018 05:45:33
%S 3,15,81,423,2247,11925,63291,335943,1783137,9464655,50237151,
%T 266652213,1415355027,7512519135,39875467761,211653760983,
%U 1123430446167,5963021689365,31650938239371,167999035324503,891716879181057
%N Number of n X 2 0..2 arrays x(i,j) with each element horizontally or vertically next to at least one element with value 2-x(i,j).
%C Column 2 of A229847.
%H R. H. Hardin, <a href="/A229841/b229841.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 5*a(n-1) + 2*a(n-2) - a(n-3) - 5*a(n-4).
%F Empirical g.f.: 3*x*(1 - 3*x^3) / ((1 - x)*(1 - 4*x - 6*x^2 - 5*x^3)). - _Colin Barker_, Mar 17 2018
%e Some solutions for n=3:
%e ..0..2....2..1....2..0....0..2....0..2....2..0....1..1....1..1....2..0....0..1
%e ..2..0....0..1....0..0....1..1....2..1....2..0....0..1....2..2....1..1....2..1
%e ..0..2....2..1....2..2....2..0....0..1....1..1....2..1....0..0....0..2....1..1
%Y Cf. A229847.
%K nonn
%O 1,1
%A _R. H. Hardin_, Oct 01 2013
| 