A183314 Number of n X 2 binary arrays with an element zero only if there are an even number of ones to its left and an even number of ones above it.

3, 6, 13, 27, 57, 119, 250, 523, 1097, 2297, 4815, 10086, 21137, 44283, 92793, 194419, 407378, 853559, 1788481, 3747361, 7851867, 16451910, 34471669, 72228171, 151339401, 317100335, 664418698, 1392152131, 2916968489, 6111905849

Offset

1,1

Comments

Column 2 of A183322.

Is this related to A131246?

Links

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

Formula

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

Empirical g.f.: x*(3 + 3*x - 2*x^2 - x^3) / (1 - x - 3*x^2 + x^3 + x^4). - Colin Barker, Mar 27 2018

Example

Some solutions for 5 X 2.
..0..0....1..1....1..1....1..1....0..1....0..0....0..0....0..1....0..0....0..0
..0..0....1..1....1..1....1..1....0..1....0..1....0..1....0..1....0..0....0..1
..1..1....0..1....0..0....0..0....0..0....0..1....0..1....0..1....1..1....0..1
..1..1....0..1....0..1....0..0....1..1....0..1....0..0....0..1....1..1....1..1
..1..1....0..0....0..1....0..0....1..1....1..1....1..1....0..0....0..1....1..1

Crossrefs

Cf. A131246, A183322.

Sequence in context: A267604 A099036 A131246 * A036886 A052251 A032253

Adjacent sequences: A183311 A183312 A183313 * A183315 A183316 A183317

Keyword

nonn

Author

R. H. Hardin, Jan 03 2011

Status

approved