A229841 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).

3, 15, 81, 423, 2247, 11925, 63291, 335943, 1783137, 9464655, 50237151, 266652213, 1415355027, 7512519135, 39875467761, 211653760983, 1123430446167, 5963021689365, 31650938239371, 167999035324503, 891716879181057

Offset: 1

Author

R. H. Hardin, Oct 01 2013

Keywords

• nonn

Comments

Column 2 of A229847.

Examples

			Some solutions for n=3:
..0..2....2..1....2..0....0..2....0..2....2..0....1..1....1..1....2..0....0..1
..2..0....0..1....0..0....1..1....2..1....2..0....0..1....2..2....1..1....2..1
..0..2....2..1....2..2....2..0....0..1....1..1....2..1....0..0....0..2....1..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A229847.

Formula

Empirical: a(n) = 5*a(n-1) + 2*a(n-2) - a(n-3) - 5*a(n-4).

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