A228662 Number of 3 X n binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally.

4, 5, 34, 78, 335, 968, 3556, 11245, 38986, 127662, 433015, 1437072, 4833924, 16125205, 54068594, 180718798, 605223135, 2024416088, 6776576996, 22673534845, 75884451226, 253927226542, 849793486215, 2843728075552, 9516580935684

Offset: 1

Author

R. H. Hardin, Aug 29 2013

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 3 of A228660.

Formula

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

Empirical g.f.: x*(4 - 3*x) / (1 - 2*x - 6*x^2 + 5*x^3). - Colin Barker, Sep 12 2018