A233013 Number of n X 3 0..3 arrays with no element x(i,j) adjacent to value 3-x(i,j) horizontally or vertically, top left element zero, and 1 appearing before 2 in row major order.

5, 74, 1202, 19643, 321125, 5249894, 85827722, 1403151863, 22939385045, 375023830514, 6131065553042, 100233536530883, 1638664887623765, 26789662490893934, 437969972870249162, 7160138624410348703

Offset

1,1

Links

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

Formula

Empirical: a(n) = 19*a(n-1) - 45*a(n-2) + 27*a(n-3).

Empirical g.f.: x*(5 - 21*x + 21*x^2) / ((1 - x)*(1 - 18*x + 27*x^2)). - Colin Barker, Oct 06 2018

Example

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

Crossrefs

Column 3 of A233018.

Sequence in context: A334258 A322446 A065894 * A126740 A251666 A192564

Adjacent sequences: A233010 A233011 A233012 * A233014 A233015 A233016

Keyword

nonn

Author

R. H. Hardin, Dec 03 2013

Status

approved