A233077 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally or antidiagonally, top left element zero, and 1 appearing before 2 in row major order.

5, 95, 1985, 41675, 875165, 18378455, 385947545, 8104898435, 170202867125, 3574260209615, 75059464401905, 1576248752439995, 33101223801239885, 695125699826037575, 14597639696346789065, 306550433623282570355

Offset

1,1

Links

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

Formula

Empirical: a(n) = 22*a(n-1) - 21*a(n-2).

Conjectures from Colin Barker, Oct 07 2018: (Start)

G.f.: 5*x*(1 - 3*x) / ((1 - x)*(1 - 21*x)).

a(n) = (7 + 3^(1+n)*7^n) / 14.

(End)

Example

Some solutions for n=4:
..0..1..3....0..1..0....0..1..1....0..0..1....0..0..0....0..1..1....0..0..0
..3..1..3....1..0..0....0..0..1....1..1..3....0..0..1....0..0..2....1..0..0
..0..1..3....0..2..3....2..0..1....0..1..0....2..3..3....2..3..1....0..1..1
..1..1..0....0..2..0....2..0..2....0..0..2....1..3..1....1..0..1....1..1..0

Crossrefs

Column 3 of A233082.

Sequence in context: A362481 A359271 A363844 * A182960 A241998 A263394

Adjacent sequences: A233074 A233075 A233076 * A233078 A233079 A233080

Keyword

nonn

Author

R. H. Hardin, Dec 03 2013

Status

approved