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A207347 Number of 3 X n 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 0 and 1 1 1 vertically. 1
6, 36, 84, 192, 426, 858, 1704, 3330, 6390, 12150, 22938, 43044, 80424, 149766, 278160, 515568, 954072, 1763304, 3255666, 6006342, 11074116, 20407650, 37592934, 69228330, 127454070, 234605316, 431771328, 794539482, 1461954876, 2689788048 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A207346.

LINKS

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

FORMULA

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

Empirical g.f.: 6*x*(1 + x)*(1 + 3*x - x^2 + 4*x^3 - x^4 + x^5) / ((1 - x - x^3)*(1 - x - x^2 - x^3)). - Colin Barker, Jun 22 2018

EXAMPLE

Some solutions for n=4:

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

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

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

CROSSREFS

Cf. A207346.

Sequence in context: A207264 A207270 A207763 * A207769 A207896 A207656

Adjacent sequences:  A207344 A207345 A207346 * A207348 A207349 A207350

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 17 2012

STATUS

approved

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Last modified December 3 13:27 EST 2021. Contains 349463 sequences. (Running on oeis4.)