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A232331 Number of nX4 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally, with no adjacent elements equal 1
6, 32, 154, 734, 3472, 16338, 76630, 358656, 1676330, 7828014, 36533360, 170436130, 794923238, 3706958560, 17284778298, 80589690622, 375729468240, 1751693001458, 8166429157878, 38071572583616, 177486683779786, 827424427937102 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A232335

LINKS

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

FORMULA

Empirical: a(n) = 7*a(n-1) -9*a(n-2) -8*a(n-3) -4*a(n-4).

Empirical: G.f.: -2*x*(-3+5*x+8*x^2+4*x^3) / ( 1-7*x+9*x^2+8*x^3+4*x^4 ). - R. J. Mathar, Nov 24 2013

EXAMPLE

Some solutions for n=7

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

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

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

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

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

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

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

CROSSREFS

Sequence in context: A243026 A242542 A046725 * A231992 A292044 A006668

Adjacent sequences:  A232328 A232329 A232330 * A232332 A232333 A232334

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 22 2013

STATUS

approved

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Last modified October 16 15:49 EDT 2019. Contains 328101 sequences. (Running on oeis4.)