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A183331 Number of n X 3 binary arrays with each 1 adjacent to exactly two 0s. 1
2, 10, 26, 66, 194, 534, 1468, 4102, 11402, 31644, 87958, 244418, 679050, 1886836, 5242786, 14567272, 40476178, 112465998, 312494040, 868285644, 2412590548, 6703544510, 18626248566, 51754284540, 143802757136, 399565623778 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A183335.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..200

FORMULA

Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) + a(n-5) + 3*a(n-6) - a(n-7) - 3*a(n-8) - a(n-9).

Empirical g.f.: 2*x*(1 + 3*x + 2*x^2 - x^3 + 3*x^4 - 4*x^6 - 2*x^7) / (1 - 2*x - x^2 - 3*x^3 - x^5 - 3*x^6 + x^7 + 3*x^8 + x^9). - Colin Barker, Mar 27 2018

EXAMPLE

Some solutions for 4 X 3:

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

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

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

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

CROSSREFS

Cf. A183335.

Sequence in context: A131130 A099969 A241688 * A324914 A025589 A084182

Adjacent sequences:  A183328 A183329 A183330 * A183332 A183333 A183334

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 03 2011

STATUS

approved

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Last modified January 18 14:01 EST 2020. Contains 331010 sequences. (Running on oeis4.)