A282990 Number of nX2 0..1 arrays with no 1 equal to more than one of its horizontal and vertical neighbors.

4, 11, 33, 98, 291, 865, 2570, 7637, 22693, 67432, 200373, 595405, 1769236, 5257255, 15621845, 46420050, 137936399, 409875693, 1217938738, 3619084505, 10754048825, 31955475472, 94955158681, 282157659273, 838426745764, 2491370993875

Offset: 1

Author

R. H. Hardin, Feb 26 2017

Keywords

• nonn

Comments

Column 2 of A282996, A295275.

Examples

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

Links

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

Crossrefs

Cf. A282996, A295275.

Formula

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

Empirical: G.f.: -x*(-4-3*x+x^2+x^3)/(1-2*x-3*x^2+x^4) . - R. J. Mathar, Mar 02 2017