login
A184189
Half the number of (n+1) X 2 binary arrays with no 2 X 2 subblock containing exactly one 1.
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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 10 2011
STATUS
approved