A259244 Number of (n+1) X (2+1) 0..1 arrays with each 2 X 2 subblock having clockwise pattern 0000 0011 or 0111.

21, 65, 192, 581, 1733, 5216, 15613, 46897, 140568, 421901, 1265269, 3796472, 11387877, 34165857, 102492080, 307483605, 922431077, 2767317200, 8301880013, 24905716177, 74716886152, 224150891421, 672451700885, 2017355772136

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(21 + 2*x - 87*x^2 - 24*x^3) / ((1 - 3*x)*(1 - 4*x^2 - x^3)). - Colin Barker, Dec 24 2018

Example

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

Crossrefs

Column 2 of A259250.

Sequence in context: A014641 A259677 A089115 * A020309 A048713 A219814

Adjacent sequences: A259241 A259242 A259243 * A259245 A259246 A259247

Keyword

nonn

Author

R. H. Hardin, Jun 22 2015

Status

approved