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A195964
Number of n X 3 0..4 arrays with each element equal to the number its horizontal and vertical neighbors equal to itself.
1
2, 2, 5, 7, 14, 25, 35, 56, 107, 173, 284, 491, 805, 1338, 2299, 3817, 6348, 10741, 17955, 29996, 50517, 84551, 141438, 237601, 398131, 666648, 1118507, 1874589, 3140516, 5266459, 8827461, 14792378, 24799555, 41569097, 69668012, 116786117, 195757315
OFFSET
1,1
COMMENTS
Column 3 of A195969.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-3) +2*a(n-4) +2*a(n-5) +4*a(n-6) -a(n-9) for n>11.
Empirical g.f.: x*(2 + 2*x + 5*x^2 + 3*x^3 + 6*x^4 + 7*x^5 - x^6 - 4*x^7 - 5*x^8 - x^9 - 2*x^10) / (1 - 2*x^3 - 2*x^4 - 2*x^5 - 4*x^6 + x^9). - Colin Barker, May 08 2018
EXAMPLE
All solutions for n=4:
..0..1..1....2..2..2....2..2..2....0..1..1....1..1..0....2..2..2....1..1..0
..1..2..2....2..0..2....2..0..2....2..2..2....2..2..1....2..1..2....2..2..2
..1..2..2....2..2..2....2..2..2....2..0..2....2..2..1....2..1..2....2..0..2
..0..1..1....1..1..0....0..1..1....2..2..2....1..1..0....2..2..2....2..2..2
CROSSREFS
Cf. A195969.
Sequence in context: A259864 A028303 A255063 * A375079 A238422 A047083
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 25 2011
STATUS
approved