A238908 Number of (n+1) X (3+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.

54, 486, 17496, 408726, 10789686, 274834944, 7073353350, 181499433750, 4661259221016, 119679993219366, 3073064486445414, 78906460267708416, 2026077840987433686, 52023421931028414534, 1335801507196609225944

Offset

1,1

Links

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

Formula

Empirical: a(n) = 22*a(n-1) + 120*a(n-2) - 678*a(n-3) + 522*a(n-4) + 432*a(n-5) - 81*a(n-6).

Empirical g.f.: 54*x*(1 - 13*x + 6*x^2 + 39*x^3 - 9*x^4) / ((1 - 28*x + 60*x^2 - 9*x^3)*(1 + 6*x - 12*x^2 - 9*x^3)). - Colin Barker, Oct 24 2018

Example

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

Crossrefs

Column 3 of A238912.

Sequence in context: A230921 A239687 A192216 * A233364 A222968 A228016

Adjacent sequences: A238905 A238906 A238907 * A238909 A238910 A238911

Keyword

nonn

Author

R. H. Hardin, Mar 07 2014

Status

approved