A183814 1/81 the number of (n+1) X 4 0..2 arrays with no 2 X 2 subblock being a reflection across the shared element pair of any horizontal or vertical neighbor.

64, 3256, 163208, 8231592, 414246824, 20864057480, 1050517114472, 52900274426120, 2663752907479720, 134133403972622152, 6754253376412941416, 340109468142471752968, 17126149629153540430376, 862384378029691966195144

Offset: 1

Author

R. H. Hardin, Jan 07 2011

Keywords

• nonn

Comments

Column 3 of A183819.

Examples

			Some solutions with upper left block zero for 3 X 4:
..0..0..0..1....0..0..0..1....0..0..0..2....0..0..2..2....0..0..0..2
..0..0..1..1....0..0..1..2....0..0..1..1....0..0..1..0....0..0..2..0
..2..1..1..1....2..0..2..1....2..2..2..1....2..0..0..1....0..2..0..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..41

Crossrefs

Cf. A183819.

Formula

Empirical: a(n) = 43*a(n-1) + 560*a(n-2) - 10054*a(n-3) + 24480*a(n-4) + 45920*a(n-5).

Empirical g.f.: 8*x*(8 + 63*x - 1580*x^2 + 4218*x^3 + 7624*x^4) / (1 - 43*x - 560*x^2 + 10054*x^3 - 24480*x^4 - 45920*x^5). - Colin Barker, Apr 04 2018