A228278 Number of n X 3 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically or nw-se diagonally.

2, 3, 13, 35, 112, 337, 1034, 3154, 9637, 29431, 89895, 274564, 838609, 2561372, 7823242, 23894643, 72981777, 222909351, 680835436, 2079486057, 6351405998, 19399196250, 59251261117, 180972030923, 552745635451, 1688259428536

Offset: 1

Author

R. H. Hardin, Aug 19 2013

Keywords

• nonn

Comments

Column 3 of A228285.

Examples

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

Links

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

Crossrefs

See A228277-A228285, especially the latter.

Formula

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

G.f.: x*(2 + x - x^3) / ((1 + x)*(1 - 2*x - 3*x^2 - x^3 + x^4)). - Colin Barker, Mar 16 2018

Extensions

Edited by N. J. A. Sloane, Aug 22 2013