A208790 Number of n X 2 0..2 arrays with no element equal the average of immediate neighbors vertically above, diagonally above and left, and horizontally left of it.

6, 30, 160, 852, 4540, 24192, 128904, 686872, 3659968, 19502160, 103916912, 553720576, 2950493472, 15721676640, 83772786944, 446382452544, 2378544288704, 12674048980992, 67533539958912, 359851776690560, 1917466505378816

Offset

1,1

Comments

Column 2 of A208796.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 16*a(n-2) + 10*a(n-3) - 4*a(n-4).

Empirical g.f.: 2*x*(1 + x)*(3 + 6*x - 4*x^2) / (1 - 2*x - 16*x^2 - 10*x^3 + 4*x^4). - Colin Barker, Jul 06 2018

Example

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

Crossrefs

Cf. A208796.

Sequence in context: A152224 A238769 A280474 * A026112 A038155 A026331

Adjacent sequences: A208787 A208788 A208789 * A208791 A208792 A208793

Keyword

nonn

Author

R. H. Hardin, Mar 01 2012

Status

approved