A231138 Number of (n+1) X (1+1) 0..2 arrays with no element equal to a strict majority of its horizontal and vertical neighbors, with upper left element zero.

18, 100, 570, 3234, 18376, 104386, 593022, 3368932, 19138850, 108727402, 617678248, 3509017866, 19934661174, 113248415924, 643362012010, 3654926870610, 20763567293192, 117957415290738, 670113744215758

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - 11*a(n-3) + 4*a(n-4).

Empirical g.f.: 2*x*(9 - 4*x - 15*x^2 + 6*x^3) / (1 - 6*x + 11*x^3 - 4*x^4). - Colin Barker, Sep 26 2018

Example

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

Crossrefs

Column 1 of A231144.

Sequence in context: A064604 A359435 A301542 * A140198 A107600 A229326

Adjacent sequences: A231135 A231136 A231137 * A231139 A231140 A231141

Keyword

nonn

Author

R. H. Hardin, Nov 04 2013

Status

approved