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A210088 Number of (n+1) X 2 0..2 arrays containing all values 0..2 with every 2 X 2 subblock having one or two distinct values, and new values 0..2 introduced in row major order. 1
0, 9, 90, 657, 4230, 25533, 148410, 842265, 4704750, 25994709, 142528770, 777216177, 4221470070, 22863109293, 123563792970, 666766408905, 3593844532350, 19354295087109, 104165322930450, 560359838547297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 1 of A210095.

LINKS

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

FORMULA

Empirical: a(n) = 10*a(n-1) - 27*a(n-2) + 10*a(n-3) + 8*a(n-4).

Empirical g.f.: 9*x^2 / ((1 - x)*(1 - 4*x)*(1 - 5*x - 2*x^2)). - Colin Barker, Jul 14 2018

EXAMPLE

Some solutions for n=4:

..0..0....0..0....0..1....0..0....0..1....0..0....0..0....0..1....0..0....0..1

..1..0....0..0....0..0....1..1....1..1....0..1....0..1....1..1....0..1....0..1

..1..0....0..0....1..0....1..0....0..0....0..0....0..0....1..0....0..0....0..0

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

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

CROSSREFS

Cf. A210095.

Sequence in context: A165135 A277105 A180289 * A261315 A270242 A054616

Adjacent sequences:  A210085 A210086 A210087 * A210089 A210090 A210091

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 17 2012

STATUS

approved

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Last modified September 15 12:22 EDT 2019. Contains 327078 sequences. (Running on oeis4.)