A221887 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

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