A205818 Number of (n+1) X 4 0..2 arrays with the number of clockwise edge increases in every 2 X 2 subblock unequal to the number of counterclockwise edge increases.

180, 714, 2880, 12318, 53100, 230532, 1002240, 4361064, 18980472, 82617132, 359622708, 1565418528, 6814215036, 29662110636, 129118523304, 562050276348, 2446593518052, 10649972628456, 46359118343628, 201800318106108

Offset: 1

Author

R. H. Hardin, Feb 01 2012

Keywords

• nonn

Comments

Column 3 of A205823.

Examples

			Some solutions for n=4:
..1..0..0..2....0..0..2..2....2..2..2..0....1..1..1..0....1..2..1..1
..1..2..1..2....2..1..1..0....1..0..1..0....2..0..2..2....1..0..0..2
..1..0..1..0....2..0..2..2....1..2..1..2....2..1..1..0....2..2..1..1
..2..0..2..2....1..1..1..0....0..2..0..2....2..0..2..2....1..0..0..2
..2..1..1..0....2..0..2..0....0..1..1..1....2..1..1..0....1..2..1..2
		

Links

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

Crossrefs

Cf. A205823.

Formula

Empirical: a(n) = 3*a(n-1) + 10*a(n-2) - 13*a(n-3) - 25*a(n-4) + 12*a(n-5) + 18*a(n-6) - 2*a(n-8).

Empirical g.f.: 6*x*(30 + 29*x - 177*x^2 - 187*x^3 + 188*x^4 + 197*x^5 - 5*x^6 - 23*x^7) / ((1 - x - x^2)*(1 - 2*x - 11*x^2 + 14*x^4 + 2*x^5 - 2*x^6)). - Colin Barker, Jun 12 2018