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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 17 16:49 EDT 2021. Contains 345085 sequences. (Running on oeis4.)