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A205980 Number of (n+1) X 3 0..2 arrays with every 2 X 3 or 3 X 2 subblock having exactly two clockwise edge increases. 1
423, 1980, 8004, 33504, 140802, 591336, 2482596, 10425528, 43778766, 183827574, 771932004, 3241441338, 13611219624, 57155642244, 240004267116, 1007811633786, 4231945805718, 17770531374384, 74620975427586, 313344031580448 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A205986.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 7*a(n-2) + 26*a(n-3) + 5*a(n-4) - 12*a(n-6) - 4*a(n-7) for n>9.

Empirical g.f.: 3*x*(141 + 519*x + 1021*x^2 + 214*x^3 - 775*x^4 - 666*x^5 - 134*x^6 + 220*x^7 + 96*x^8) / (1 - x - 7*x^2 - 26*x^3 - 5*x^4 + 12*x^6 + 4*x^7). - Colin Barker, Jun 13 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

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

CROSSREFS

Cf. A205986.

Sequence in context: A231939 A203099 A096024 * A206662 A205831 A206408

Adjacent sequences:  A205977 A205978 A205979 * A205981 A205982 A205983

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 02 2012

STATUS

approved

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Last modified January 23 20:39 EST 2021. Contains 340386 sequences. (Running on oeis4.)