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A221324 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2. 1
17, 866, 46105, 2460824, 131347807, 7010554450, 374176705928, 19970973695923, 1065911268786396, 56890876705125765, 3036435876484206258, 162063633563069131638, 8649818983278197229631, 461666606875092805859284 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A221328.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..118

FORMULA

Empirical: a(n) = 91*a(n-1) -2497*a(n-2) +29072*a(n-3) -168762*a(n-4) +513070*a(n-5) -765950*a(n-6) +359339*a(n-7) +283374*a(n-8) -252113*a(n-9) -12688*a(n-10) +38079*a(n-11) -6354*a(n-12) +289*a(n-13).

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Sequence in context: A173983 A231778 A281428 * A124235 A218660 A086265

Adjacent sequences:  A221321 A221322 A221323 * A221325 A221326 A221327

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 11 2013

STATUS

approved

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Last modified June 15 10:14 EDT 2021. Contains 345048 sequences. (Running on oeis4.)