A228678 Number of nX3 binary arrays with no two ones adjacent horizontally, diagonally or antidiagonally.

5, 19, 77, 313, 1277, 5215, 21305, 87049, 355685, 1453363, 5938613, 24265921, 99153677, 405154783, 1655515121, 6764650225, 27641241413, 112945711027, 461510880221, 1885793543785, 7705597945181, 31486076453887, 128656207802537

Offset: 1

Author

R. H. Hardin Aug 30 2013

Keywords

• nonn

Comments

Column 3 of A228683

Examples

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

Links

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

Formula

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

Empirical: G.f. -x*(-5+6*x+3*x^2) / ( 1-5*x+3*x^2+3*x^3 ). - R. J. Mathar, Aug 31 2013