A208029 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 0 1 vertically.

9, 81, 279, 1377, 5895, 26685, 118179, 527913, 2350215, 10476981, 46680363, 208028817, 926993439, 4130894781, 18407971395, 82029484089, 365538508695, 1628908337349, 7258719524571, 32346212936481, 144140772230991

Offset: 1

Author

R. H. Hardin, Feb 22 2012

Keywords

• nonn

Comments

Row 4 of A208028.

Examples

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

Links

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

Crossrefs

Cf. A208028.

Formula

Empirical: a(n) = 2*a(n-1) + 11*a(n-2) + 2*a(n-3) - 10*a(n-4).

Empirical g.f.: 9*x*(1 - x)*(1 + 8*x + 10*x^2) / (1 - 2*x - 11*x^2 - 2*x^3 + 10*x^4). - Colin Barker, Jun 26 2018