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A221257 Number of 3Xn arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2 1
0, 16, 30, 2116, 22268, 488601, 7356420, 132273001, 2175160988, 37343243536, 627439570380, 10652755988736, 179923226827008, 3046558564618321, 51520912019433840, 871812703964410321, 14747896839403221578 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row 3 of A221255

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..36

FORMULA

Empirical: a(n) = 21*a(n-1) +21*a(n-2) -1891*a(n-3) +4713*a(n-4) +31527*a(n-5) -98973*a(n-6) -92217*a(n-7) +299577*a(n-8) -27117*a(n-9) +103383*a(n-10) -393*a(n-11) +6211*a(n-12) +69*a(n-13) +69*a(n-14) +a(n-15) for n>18

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A145581 A186453 A129617 * A194122 A257349 A167997

Adjacent sequences:  A221254 A221255 A221256 * A221258 A221259 A221260

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 06 2013

STATUS

approved

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Last modified October 18 03:25 EDT 2021. Contains 348065 sequences. (Running on oeis4.)