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A206112 Number of (n+1) X 3 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly two counterclockwise and two clockwise edge increases. 1
1140, 5228, 22624, 111552, 588840, 3048096, 16072760, 84203240, 442219464, 2322616208, 12190484896, 64028249688, 336134793648, 1765105097640, 9267826715912, 48663053519336, 255518422362912, 1341650195416352 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A206118.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 19*a(n-2) + 6*a(n-3) - 90*a(n-4) + 19*a(n-5) + 45*a(n-6) for n>8.

Empirical g.f.: 4*x*(285 + 737*x - 2373*x^2 - 9967*x^3 + 1778*x^4 + 16011*x^5 + 1206*x^6 - 3645*x^7) / ((1 - x)*(1 - x - x^2)*(1 - 19*x^2 - 45*x^3)). - Colin Barker, Jun 13 2018

EXAMPLE

Some solutions for n=4:

..2..3..2....0..1..1....1..0..0....0..3..2....2..0..0....3..1..2....2..3..2

..3..2..2....0..2..3....0..0..3....3..2..2....1..2..2....1..1..2....2..3..3

..2..2..1....0..1..3....1..1..0....2..2..3....2..2..1....1..3..0....0..1..1

..2..0..2....0..2..3....2..1..1....1..1..2....0..0..2....2..0..0....1..1..2

..0..2..2....0..1..3....3..2..1....2..1..1....1..0..0....0..0..1....2..2..3

CROSSREFS

Cf. A206118.

Sequence in context: A014365 A027545 A113708 * A232133 A261572 A252476

Adjacent sequences:  A206109 A206110 A206111 * A206113 A206114 A206115

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 03 2012

STATUS

approved

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Last modified December 8 19:21 EST 2021. Contains 349596 sequences. (Running on oeis4.)