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

Author

R. H. Hardin, Jun 22 2015

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 2 of A259250.

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