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A221796
Number of n X 3 arrays of occupancy after each element moves to some horizontal or vertical neighbor, without move-in move-out straight through or left turns.
1
0, 12, 12, 207, 470, 4073, 13314, 85974, 338148, 1892213, 8198076, 42661873, 194441436, 974764224, 4561903748, 22432271947, 106441266034, 518196714761, 2476544809950, 11994439907546, 57537238641980, 277917546512145
OFFSET
1,2
COMMENTS
Column 3 of A221800.
LINKS
FORMULA
Empirical: a(n) = 27*a(n-2) + 14*a(n-3) - 165*a(n-4) - 20*a(n-5) + 329*a(n-6) - 48*a(n-7) - 131*a(n-8) - 34*a(n-9) + 9*a(n-10).
Empirical g.f.: x^2*(12 + 12*x - 117*x^2 - 22*x^3 + 296*x^4 - 54*x^5 - 130*x^6 - 34*x^7 + 9*x^8) / (1 - 27*x^2 - 14*x^3 + 165*x^4 + 20*x^5 - 329*x^6 + 48*x^7 + 131*x^8 + 34*x^9 - 9*x^10). - Colin Barker, Aug 11 2018
EXAMPLE
Some solutions for n=3:
..1..1..1....0..1..1....0..2..0....1..1..1....0..2..1....1..1..1....1..2..1
..1..0..2....2..2..1....1..2..1....1..0..1....1..1..1....1..2..1....1..0..1
..1..1..1....0..1..1....1..1..1....1..2..1....1..1..1....0..2..0....1..1..1
CROSSREFS
Cf. A221800.
Sequence in context: A178341 A165833 A038338 * A222298 A122253 A156456
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 26 2013
STATUS
approved