A233093 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally, diagonally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order.

5, 65, 941, 13721, 200165, 2920145, 42601181, 621496841, 9066845525, 132273701825, 1929704454221, 28151924602361, 410700642310085, 5991598087037105, 87409767451696061, 1275196923253218281

Offset

1,1

Links

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

Formula

Empirical: a(n) = 16*a(n-1) - 21*a(n-2) + 6*a(n-3).

Empirical g.f.: x*(5 - 15*x + 6*x^2) / ((1 - x)*(1 - 15*x + 6*x^2)). - Colin Barker, Oct 07 2018

Example

Some solutions for n=5:
..0..0..1....0..0..0....0..1..0....0..0..0....0..0..1....0..0..1....0..0..1
..1..1..1....1..1..1....0..2..0....0..1..0....2..0..0....1..1..1....0..1..0
..0..1..0....0..1..0....2..2..0....3..1..3....0..0..2....3..1..3....1..1..0
..3..2..3....0..2..3....2..2..3....0..2..0....1..0..0....3..2..0....3..1..3
..2..3..2....2..2..2....3..3..2....3..2..2....2..0..2....3..2..3....3..1..3

Crossrefs

Column 3 of A233098.

Sequence in context: A155653 A087453 A103974 * A208588 A249930 A207262

Adjacent sequences: A233090 A233091 A233092 * A233094 A233095 A233096

Keyword

nonn

Author

R. H. Hardin, Dec 04 2013

Status

approved