A205737 - OEIS

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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.

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

R. H. Hardin, Table of n, a(n) for n = 1..210

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

Adjacent sequences: A205734 A205735 A205736 * A205738 A205739 A205740

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 30 2012

STATUS

approved