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A221770 Number of nX3 arrays of occupancy after each element stays put or moves to some horizontal or vertical neighbor, without move-in move-out left turns 1
8, 240, 7371, 225873, 6916881, 211747695, 6481445220, 198382906386, 6071963365426, 185845222595198, 5688172415683436, 174098004679065547, 5328619769994758026, 163093117823302631286, 4991792532904719775902 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A221773

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..51

FORMULA

Empirical: a(n) = 84*a(n-1) -2905*a(n-2) +56716*a(n-3) -709393*a(n-4) +6061574*a(n-5) -36651293*a(n-6) +159758786*a(n-7) -505601632*a(n-8) +1158517028*a(n-9) -1893716704*a(n-10) +2129563639*a(n-11) -1500050698*a(n-12) +447745570*a(n-13) +217671350*a(n-14) -275450748*a(n-15) +109467496*a(n-16) -17701536*a(n-17) +715760*a(n-18)

EXAMPLE

Some solutions for n=3

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

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

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

CROSSREFS

Sequence in context: A254927 A221466 A067360 * A007060 A319851 A320605

Adjacent sequences:  A221767 A221768 A221769 * A221771 A221772 A221773

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 25 2013

STATUS

approved

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Last modified May 23 13:16 EDT 2019. Contains 323514 sequences. (Running on oeis4.)