A221357 Number of n X 2 arrays of occupancy after each element moves to some horizontal, vertical or antidiagonal neighbor, with no 2-loops and with no occupancy greater than 2.

0, 5, 39, 292, 2088, 14799, 104532, 737498, 5200799, 36668393, 258507703, 1822366939, 12846614967, 90560097250, 638385027225, 4500153384191, 31722787454665, 223622276075576, 1576371711149454, 11112253094012636

Offset

1,2

Comments

Column 2 of A221361.

Links

R. H. Hardin, Table of n, a(n) for n = 1..192

Formula

Empirical: a(n) = 12*a(n-1) - 38*a(n-2) + 14*a(n-3) + 59*a(n-4) - 21*a(n-5) - 33*a(n-6) + 16*a(n-7).

Empirical g.f.: x^2*(5 - 21*x + 14*x^2 - 4*x^3 - 2*x^4 + 4*x^5) / (1 - 12*x + 38*x^2 - 14*x^3 - 59*x^4 + 21*x^5 + 33*x^6 - 16*x^7). - Colin Barker, Aug 05 2018

Example

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

Crossrefs

Cf. A221361.

Sequence in context: A202391 A053573 A003482 * A201442 A135849 A105426

Adjacent sequences: A221354 A221355 A221356 * A221358 A221359 A221360

Keyword

nonn

Author

R. H. Hardin, Jan 12 2013

Status

approved