A221887 Number of nX3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, without 2-loops or left turns

0, 8, 0, 90, 204, 1297, 4608, 23159, 92312, 425249, 1799292, 7982268, 34469356, 151243634, 657198136, 2872557590, 12512098304, 54609983231, 238067509008, 1038559461306, 4528789386340, 19753331212394, 86145964341528

Offset

1,2

Comments

Column 3 of A221890

Links

R. H. Hardin, Table of n, a(n) for n = 1..48

Formula

Empirical: a(n) = 14*a(n-2) +28*a(n-3) +a(n-4) -104*a(n-5) -92*a(n-6) +84*a(n-7) +19*a(n-8) -4*a(n-9) +75*a(n-10) -15*a(n-12) -8*a(n-13) +4*a(n-14)

Example

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

Crossrefs

Sequence in context: A350452 A079137 A181689 * A277257 A121770 A221379

Adjacent sequences: A221884 A221885 A221886 * A221888 A221889 A221890

Keyword

nonn

Author

R. H. Hardin Jan 30 2013

Status

approved