A221297 Number of n X 2 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, with no occupancy greater than 2.

3, 19, 137, 1001, 7305, 53291, 388741, 2835697, 20685009, 150886255, 1100633309, 8028513089, 58563541437, 427188362291, 3116100301045, 22730208012457, 165804141741249, 1209448362939775, 8822248421700605, 64353360753783545

Offset

1,1

Comments

Column 2 of A221303.

Links

R. H. Hardin, Table of n, a(n) for n = 1..113

Formula

Empirical: a(n) = 11*a(n-1) - 27*a(n-2) - a(n-3) + 8*a(n-4) - 16*a(n-5) - 6*a(n-6) + 2*a(n-7).

Empirical g.f.: x*(3 - 14*x + 9*x^2 + 10*x^3 - 12*x^4 - 4*x^5 + 2*x^6) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Mar 14 2018

Example

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

Crossrefs

Cf. A221303.

Sequence in context: A215852 A105797 A278189 * A138513 A321515 A094661

Adjacent sequences: A221294 A221295 A221296 * A221298 A221299 A221300

Keyword

nonn

Author

R. H. Hardin, Jan 09 2013

Status

approved