A201535 Number of nX4 0..2 arrays with rows and columns lexicographically nondecreasing and every element equal to at least one horizontal or vertical neighbor.

6, 69, 633, 7799, 91425, 983981, 9526987, 82847704, 652848538, 4712696751, 31480011434, 196280028176, 1150650039753, 6380377582098, 33631853768986, 169225758487160, 815686475352515, 3777731764480697, 16854911299206527

Offset: 1

Author

R. H. Hardin Dec 02 2011

Keywords

• nonn

Comments

Column 4 of A201539

Examples

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

Links

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

Formula

Empirical: a(n) is a polynomial of degree 80 for n>43