A240888 Number of n X 3 0..2 arrays with no element equal to a different number of vertical neighbors than horizontal neighbors, with new values 0..2 introduced in row major order.

2, 11, 57, 289, 1485, 7609, 38981, 199761, 1023597, 5245049, 26876501, 137719297, 705694973, 3616090505, 18529407461, 94947553233, 486525966349, 2493034391385, 12774694280053, 65459511713057, 335424674724381, 1718767975363881

Offset: 1

Author

R. H. Hardin, Apr 14 2014

Keywords

• nonn

Examples

			Some solutions for n=4:
..0..1..0....0..1..2....0..1..1....0..1..0....0..1..2....0..1..1....0..1..0
..2..0..1....2..0..0....2..1..1....2..0..2....1..0..1....2..1..1....1..0..1
..0..1..2....1..0..0....1..0..2....0..2..0....2..1..0....1..2..2....0..2..0
..1..0..1....2..1..2....2..1..0....1..0..1....0..2..1....0..2..2....2..1..2
		

Links

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

Crossrefs

Column 3 of A240893.

Formula

Empirical: a(n) = 3*a(n-1) + 8*a(n-2) + 14*a(n-3) + 4*a(n-4).

Empirical g.f.: x*(2 + 5*x + 8*x^2 + 2*x^3) / (1 - 3*x - 8*x^2 - 14*x^3 - 4*x^4). - Colin Barker, Oct 29 2018