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

1,1

Comments

Column 3 of A205823.

Links

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

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

Example

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

Crossrefs

Cf. A205823.

Sequence in context: A211552 A004532 A143793 * A259312 A032774 A032776

Adjacent sequences: A205815 A205816 A205817 * A205819 A205820 A205821

Keyword

nonn

Author

R. H. Hardin, Feb 01 2012

Status

approved