A259509 Number of (n+1) X (2+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0001 0101 0111.

31, 129, 533, 2219, 9227, 38409, 159845, 665339, 2769251, 11526489, 47976173, 199690619, 831166667, 3459548649, 14399597045, 59935131419, 249466635731, 1038349453209, 4321898626973, 17988942330779, 74874972302267

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 11*a(n-2) - 4*a(n-3) - 18*a(n-4).

Empirical g.f.: x*(31 + 67*x - 66*x^2 - 142*x^3) / ((1 - 2*x^2)*(1 - 2*x - 9*x^2)). - Colin Barker, Dec 25 2018

Example

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

Crossrefs

Column 2 of A259515.

Sequence in context: A065403 A278054 A035502 * A183838 A043355 A023728

Adjacent sequences: A259506 A259507 A259508 * A259510 A259511 A259512

Keyword

nonn

Author

R. H. Hardin, Jun 29 2015

Status

approved