A232018 Number of n X 3 0..2 arrays with no element less than a strict majority of its horizontal and antidiagonal neighbors.

9, 66, 852, 11517, 156913, 2125749, 28852936, 391447970, 5311170384, 72061691152, 977727048997, 13265735926493, 179988561188366, 2442072186590951, 33133863936280024, 449557939142907661, 6099570552966630306

Offset

1,1

Links

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

Formula

Empirical: a(n) = 9*a(n-1) + 59*a(n-2) + 62*a(n-3) - 275*a(n-4) - 257*a(n-5) + 146*a(n-6) + 84*a(n-7) for n>8.

Empirical g.f.: x*(9 - 15*x - 273*x^2 - 603*x^3 + 1375*x^4 + 1668*x^5 - 778*x^6 - 504*x^7) / (1 - 9*x - 59*x^2 - 62*x^3 + 275*x^4 + 257*x^5 - 146*x^6 - 84*x^7). - Colin Barker, Oct 01 2018

Example

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

Crossrefs

Column 3 of A232023.

Sequence in context: A226201 A091647 A321945 * A231199 A354532 A332456

Adjacent sequences: A232015 A232016 A232017 * A232019 A232020 A232021

Keyword

nonn

Author

R. H. Hardin, Nov 17 2013

Status

approved