A221870 Number of nX2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, without consecutive moves in the same direction

1, 20, 162, 1442, 12688, 110720, 970828, 8489090, 74301713, 650080567, 5688284025, 49771429169, 435493321644, 3810502524152, 33341324878142, 291731631862014, 2552608002906241, 22334937934827800, 195427359369424289

Offset

1,2

Comments

Column 2 of A221873

Links

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

Formula

Empirical: a(n) = 7*a(n-1) +27*a(n-2) -77*a(n-3) -247*a(n-4) +195*a(n-5) +277*a(n-6) -51*a(n-7) -32*a(n-8) +103*a(n-9) -78*a(n-10) +25*a(n-11) -4*a(n-12)

Example

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

Crossrefs

Sequence in context: A118676 A067534 A041768 * A289181 A056114 A281204

Adjacent sequences: A221867 A221868 A221869 * A221871 A221872 A221873

Keyword

nonn

Author

R. H. Hardin Jan 28 2013

Status

approved