A259245 Number of (n+1) X (3+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0111.

48, 192, 720, 2816, 10720, 41552, 159168, 614560, 2360464, 9098240, 34986848, 134750672, 518448960, 1996103456, 7681731600, 29571245952, 113812664288, 438098128720, 1686212575424, 6490526009760, 24982143580048, 96159317085952

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 12*a(n-2) - 11*a(n-3) - 30*a(n-4).

Empirical g.f.: 16*x*(3 + 6*x - 15*x^2 - 25*x^3) / (1 - 2*x - 12*x^2 + 11*x^3 + 30*x^4). - Colin Barker, Dec 24 2018

Example

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

Crossrefs

Column 3 of A259250.

Sequence in context: A210250 A259038 A231174 * A157923 A296367 A275507

Adjacent sequences: A259242 A259243 A259244 * A259246 A259247 A259248

Keyword

nonn

Author

R. H. Hardin, Jun 22 2015

Status

approved