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A206087 Number of (n+1) X 2 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases. 1
81, 270, 972, 3564, 13608, 52812, 205416, 803844, 3153816, 12375180, 48598056, 190924452, 750064536, 2947003884, 11579514408, 45498547908, 178776400536, 702469087308, 2760220004904, 10845780014052, 42616578679704 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A206094.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - a(n-2) + 12*a(n-3) - 36*a(n-4).

Empirical g.f.: 27*x*(3 - 2*x - x^2 - 38*x^3) / ((1 - 2*x)*(1 - 2*x - 3*x^2 - 18*x^3)). - Colin Barker, Jun 13 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A206094.

Sequence in context: A206094 A202333 A207042 * A236809 A236802 A236875

Adjacent sequences:  A206084 A206085 A206086 * A206088 A206089 A206090

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 03 2012

STATUS

approved

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Last modified December 6 18:16 EST 2021. Contains 349567 sequences. (Running on oeis4.)