A208288 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 1 0 vertically.

8, 64, 216, 984, 3984, 16872, 70216, 294192, 1229400, 5142728, 21504256, 89933368, 376090120, 1572797488, 6577333928, 27506063752, 115028758000, 481043815944, 2011697870456, 8412806681456, 35181880551080, 147128631386264

Offset: 1

Author

R. H. Hardin, Feb 25 2012

Keywords

• nonn

Comments

Row 4 of A208287.

Examples

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

Links

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

Crossrefs

Cf. A208287.

Formula

Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 4*a(n-3) - 2*a(n-4) + a(n-5).

Empirical g.f.: 8*x*(1 + 5*x - 3*x^2 - 2*x^3 + x^4) / ((1 + x - x^2)*(1 - 4*x - x^2 + x^3)). - Colin Barker, Jun 30 2018