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A221226 Number of n X 2 arrays of occupancy after each element moves to some king-move neighbor, with no occupancy greater than 2. 2
1, 19, 137, 1033, 7877, 60223, 460713, 3524857, 26968225, 206327811, 1578551849, 12076946305, 92396113725, 706885768959, 5408092980713, 41375064828945, 316543208763529, 2421738125898019, 18527690050695513, 141747473284341977 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A221229.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..65

FORMULA

Empirical: a(n) = 15*a(n-1) - 71*a(n-2) + 123*a(n-3) - 78*a(n-4) + 14*a(n-5) - 12*a(n-6) + 8*a(n-7).

Empirical g.f.: x*(1 + 4*x - 77*x^2 + 204*x^3 - 150*x^4 + 28*x^5 + 8*x^6) / (1 - 15*x + 71*x^2 - 123*x^3 + 78*x^4 - 14*x^5 + 12*x^6 - 8*x^7). - Colin Barker, Mar 14 2018

EXAMPLE

Some solutions for n=3:

..0..2....1..2....1..1....2..1....2..2....1..2....0..1....1..1....0..0....1..0

..2..0....0..1....0..2....0..2....1..1....0..2....1..1....1..0....2..2....1..2

..1..1....1..1....1..1....0..1....0..0....1..0....1..2....2..1....0..2....0..2

CROSSREFS

Cf. A221229.

Sequence in context: A213122 A211092 A142746 * A139902 A140624 A244505

Adjacent sequences:  A221223 A221224 A221225 * A221227 A221228 A221229

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 05 2013

STATUS

approved

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Last modified October 17 19:44 EDT 2019. Contains 328128 sequences. (Running on oeis4.)