A208690 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 1 1 and 1 0 1 vertically.

9, 81, 189, 927, 2889, 11727, 40581, 154359, 554733, 2062215, 7512453, 27700479, 101402109, 372809655, 1367107173, 5021003151, 18423673101, 67639822407, 248247487989, 911283026751, 3344800820445, 12277727839863, 45065827217925

Offset: 1

Author

R. H. Hardin, Mar 01 2012

Keywords

• nonn

Comments

Row 4 of A208688.

Examples

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

Links

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

Crossrefs

Cf. A208688.

Formula

Empirical: a(n) = a(n-1) + 10*a(n-2) + 2*a(n-3) - 10*a(n-4).

Empirical g.f.: 9*x*(1 + 8*x + 2*x^2 - 10*x^3) / (1 - x - 10*x^2 - 2*x^3 + 10*x^4). - Colin Barker, Jul 05 2018