A238906 - OEIS

A238906

Number of (n+1) X (1+1) 0..2 arrays with no element equal to all horizontal neighbors or equal to all vertical neighbors, and new values 0..2 introduced in row major order.

3, 9, 54, 261, 1341, 6768, 34335, 173925, 881406, 4466169, 22631337, 114678144, 581102091, 2944583217, 14920910982, 75607836957, 383123064069, 1941376545072, 9837421053831, 49848574293549, 252594693861966, 1279957958047665

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) + 6*a(n-2) - 3*a(n-3).

Empirical g.f.: 3*x*(1 - x) / (1 - 4*x - 6*x^2 + 3*x^3). - Colin Barker, Oct 24 2018

EXAMPLE

Some solutions for n=5:

..0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1....0..1

..1..2....2..0....1..2....1..0....2..0....1..0....1..0....1..2....1..0....2..0

..2..0....0..1....0..2....0..1....1..2....2..0....0..1....1..2....0..1....2..1

..0..1....0..1....2..1....1..0....2..1....2..1....0..1....2..0....1..2....1..0

..2..0....1..0....1..0....1..0....0..2....1..2....2..0....1..0....0..1....2..1

..0..1....2..1....0..1....0..1....1..0....2..0....0..2....0..1....2..0....1..2

CROSSREFS

Column 1 of A238912.

Sequence in context: A038496 A175596 A261397 * A363442 A212418 A337039

Adjacent sequences: A238903 A238904 A238905 * A238907 A238908 A238909

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 07 2014

STATUS

approved