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A221241 Number of n X 3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor. 1
2, 50, 1056, 21660, 441720, 8997120, 183206016, 3730330800, 75953515968, 1546488223200, 31487986033920, 641125466910720, 13053925809145728, 265790370894192000, 5411745241852207104, 110188290202715208960 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A221245.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..119

FORMULA

Empirical: a(n) = 30*a(n-1) - 222*a(n-2) + 540*a(n-3) - 324*a(n-4).

Empirical g.f.: 2*(1 - 5*x) / (1 - 30*x + 222*x^2 - 540*x^3 + 324*x^4). - Colin Barker, Aug 04 2018

EXAMPLE

Some solutions for n=3:

..1..1..0....0..0..1....0..2..2....0..0..0....2..1..0....0..3..0....0..4..1

..1..1..1....1..4..0....0..4..1....0..5..1....0..4..0....1..3..0....0..2..0

..0..4..0....0..2..1....0..0..0....0..1..2....1..1..0....2..0..0....1..0..1

CROSSREFS

Cf. A221245.

Sequence in context: A083939 A083941 A080263 * A246071 A088920 A278456

Adjacent sequences:  A221238 A221239 A221240 * A221242 A221243 A221244

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 06 2013

STATUS

approved

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Last modified January 26 17:00 EST 2022. Contains 350599 sequences. (Running on oeis4.)