A259508 Number of (n+1) X (1+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0001 0101 0111.

11, 31, 87, 245, 689, 1939, 5455, 15349, 43185, 121507, 341871, 961893, 2706385, 7614707, 21424783, 60280917, 169606769, 477206723, 1342671919, 3777750469, 10629103249, 29906114067, 84144036943, 236748209589, 666116301873

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(11 + 9*x - 8*x^2) / (1 - 2*x - 3*x^2 + 2*x^3). - Colin Barker, Dec 25 2018

Example

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

Crossrefs

Column 1 of A259515.

Sequence in context: A072672 A072673 A250461 * A126365 A082102 A199112

Adjacent sequences: A259505 A259506 A259507 * A259509 A259510 A259511

Keyword

nonn

Author

R. H. Hardin, Jun 29 2015

Status

approved