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A205737 Number of 2 X (n+1) 0..2 arrays with every 2 X 2 subblock having the same number of clockwise edge increases as its horizontal neighbors and no 2 X 2 subblock having the same number of counterclockwise edge increases as its vertical neighbors. 3
81, 369, 1764, 8655, 43155, 218034, 1112664, 5722236, 29600808, 153794865, 801658320, 4188664470, 21924195099, 114902238879, 602752637715, 3164061809547, 16617483609822, 87305419041021, 458806978246497 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Row 1 of A205736.
LINKS
FORMULA
Empirical: a(n) = 9*a(n-1) -18*a(n-2) -15*a(n-3) +36*a(n-4) -20*a(n-5) +11*a(n-6) -2*a(n-7).
Empirical g.f.: 3*x*(27 - 120*x - 33*x^2 + 212*x^3 - 123*x^4 + 75*x^5 - 14*x^6) / ((1 - x)*(1 - 4*x + x^2 - x^3)*(1 - 4*x - 7*x^2 + 2*x^3)). - Colin Barker, Feb 23 2018
EXAMPLE
Some solutions for n=4:
..1..2..0..1..0....2..0..2..2..2....2..1..2..2..1....2..2..2..1..2
..0..2..1..2..1....0..0..2..1..2....0..1..1..1..1....1..1..1..1..1
CROSSREFS
Cf. A205736.
Sequence in context: A205917 A205909 A237843 * A236035 A236028 A233157
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 30 2012
STATUS
approved

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Last modified June 13 17:01 EDT 2024. Contains 373391 sequences. (Running on oeis4.)