A203095 Number of n X 2 0..3 arrays with every nonzero element less than or equal to some horizontal or vertical neighbor.

4, 84, 1080, 12260, 143510, 1705124, 20174774, 238288768, 2816078514, 33286887866, 393430889634, 4650009454296, 54959608405434, 649582808767618, 7677588567818968, 90743395882037312, 1072519744806185004

Offset: 1

Author

R. H. Hardin, Dec 29 2011

Keywords

• nonn

Comments

Column 2 of A203101.

Examples

			Some solutions for n=5:
..3..3....0..3....1..1....3..2....1..3....0..3....0..0....1..3....3..0....0..0
..1..1....3..3....0..1....3..1....2..3....1..3....3..0....3..3....3..3....1..2
..0..3....2..1....1..1....1..2....1..3....1..1....3..1....3..2....0..3....0..3
..1..3....1..2....3..2....0..2....2..2....0..2....2..0....2..2....2..1....3..3
..1..2....1..2....3..0....0..0....1..1....3..3....2..2....2..0....2..2....1..0
		

Links

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

Crossrefs

Cf. A203101.

Formula

Empirical: a(n) = 10*a(n-1) -a(n-2) +236*a(n-3) +270*a(n-4) +945*a(n-5) +532*a(n-6) +576*a(n-7).

Empirical g.f.: 2*x*(2 + 22*x + 122*x^2 + 300*x^3 + 543*x^4 + 472*x^5 + 288*x^6) / (1 - 10*x + x^2 - 236*x^3 - 270*x^4 - 945*x^5 - 532*x^6 - 576*x^7). - Colin Barker, Jun 04 2018