A184189 Half the number of (n+1) X 2 binary arrays with no 2 X 2 subblock containing exactly one 1.

6, 19, 60, 190, 602, 1908, 6048, 19172, 60776, 192664, 610760, 1936160, 6137792, 19457328, 61681408, 195535392, 619864096, 1965022784, 6229292160, 19747394880, 62600949632, 198450424448, 629105008768, 1994317286912, 6322158281216

Offset

1,1

Comments

Column 1 of A184197.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

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

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

Example

Some solutions for 3 X 2:
..1..1....1..0....0..1....0..1....0..1....1..1....0..1....1..0....1..0....0..1
..0..0....0..1....1..1....1..0....0..1....1..1....0..1....1..1....1..0....1..1
..0..0....0..1....0..1....0..1....1..1....0..1....1..0....0..0....0..1....1..1

Crossrefs

Cf. A184197.

Sequence in context: A272587 A125069 A080926 * A152098 A041673 A137195

Adjacent sequences: A184186 A184187 A184188 * A184190 A184191 A184192

Keyword

nonn

Author

R. H. Hardin, Jan 10 2011

Status

approved