A234826 Number of (n+1) X (2+1) 0..2 arrays with each 2 X 2 subblock having the number of clockwise edge increases less than or equal to the number of counterclockwise edge increases.

516, 9207, 161631, 2826144, 49366557, 862112943, 15054585588, 262885602843, 4590533340099, 80160252775488, 1399764282940233, 24442786354729203, 426821718006927396, 7453191942015413679, 130148180682091274007

Offset

1,1

Links

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

Formula

Empirical: a(n) = 23*a(n-1) - 102*a(n-2) + 93*a(n-3) - 9*a(n-4).

Empirical g.f.: 3*x*(172 - 887*x + 834*x^2 - 81*x^3) / (1 - 23*x + 102*x^2 - 93*x^3 + 9*x^4). - Colin Barker, Oct 16 2018

Example

Some solutions for n=3:
..1..1..0....1..0..1....0..2..0....0..0..0....1..1..0....0..0..2....1..1..0
..1..1..2....0..0..1....2..2..0....1..1..0....2..2..2....0..1..1....0..0..2
..2..2..1....2..2..0....0..2..2....0..0..2....0..2..2....0..1..2....2..2..2
..2..2..1....2..0..2....0..0..0....1..1..2....0..2..0....2..0..1....2..1..1

Crossrefs

Column 2 of A234832.

Sequence in context: A254643 A322883 A332151 * A232574 A282753 A168188

Adjacent sequences: A234823 A234824 A234825 * A234827 A234828 A234829

Keyword

nonn

Author

R. H. Hardin, Dec 31 2013

Status

approved