A233942 Number of (n+1) X (1+1) 0..2 arrays with every 2 X 2 subblock having the sum of the absolute values of the edge differences equal to 4.

44, 226, 1150, 5874, 29970, 152974, 780718, 3984650, 20336682, 103793974, 529740902, 2703678866, 13798968738, 70426836510, 359442745310, 1834515000218, 9362952299866, 47786404483974, 243891069807254, 1244765212590370

Offset

1,1

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 3*a(n-2) - 13*a(n-3) + 2*a(n-4).

Empirical g.f.: 2*x*(22 + 3*x - 56*x^2 + 9*x^3) / (1 - 5*x - 3*x^2 + 13*x^3 - 2*x^4). - Colin Barker, Oct 12 2018

Example

Some solutions for n=5:
..0..1....1..2....2..1....2..0....1..2....2..0....2..0....1..2....0..0....2..2
..0..2....0..2....1..0....1..0....1..0....1..0....0..0....1..0....2..2....0..2
..0..2....2..2....2..1....2..0....1..2....1..2....2..2....2..0....2..0....0..0
..2..2....0..1....0..0....2..2....2..1....1..0....2..0....2..2....1..1....2..0
..0..2....0..2....2..1....2..0....0..1....0..1....1..0....2..0....0..2....2..0
..0..2....2..2....0..1....1..1....2..1....0..2....0..1....0..0....2..2....2..2

Crossrefs

Column 1 of A233949.

Sequence in context: A250454 A250447 A233949 * A122245 A031175 A098826

Adjacent sequences: A233939 A233940 A233941 * A233943 A233944 A233945

Keyword

nonn

Author

R. H. Hardin, Dec 18 2013

Status

approved