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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. 1
0, 5, 39, 292, 2088, 14799, 104532, 737498, 5200799, 36668393, 258507703, 1822366939, 12846614967, 90560097250, 638385027225, 4500153384191, 31722787454665, 223622276075576, 1576371711149454, 11112253094012636 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 28 08:06 EST 2020. Contains 332321 sequences. (Running on oeis4.)