A207718 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 0 vertically.

6, 36, 114, 450, 1644, 6186, 23010, 85992, 320742, 1197318, 4467984, 16675494, 62232582, 232257108, 866792178, 3234917538, 12072868380, 45056571498, 168153392514, 627557039160, 2342074698438, 8740741860870, 32620892573088

Offset: 1

Author

R. H. Hardin, Feb 19 2012

Keywords

• nonn

Comments

Row 3 of A207717.

Examples

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

Links

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

Crossrefs

Cf. A207717.

Formula

Empirical: a(n) = 2*a(n-1) + 7*a(n-2) - a(n-3) - 4*a(n-4) + a(n-5).

Empirical g.f.: 6*x*(1 + 4*x - 4*x^3 + x^4) / ((1 + x)*(1 - 4*x + x^2)*(1 + x - x^2)). - Colin Barker, Mar 05 2018