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

1,1

Comments

Column 2 of A203101.

Links

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

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

Example

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

Crossrefs

Cf. A203101.

Sequence in context: A282588 A178208 A069441 * A006344 A203244 A245544

Adjacent sequences: A203092 A203093 A203094 * A203096 A203097 A203098

Keyword

nonn

Author

R. H. Hardin, Dec 29 2011

Status

approved