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A183331 Number of n X 3 binary arrays with each 1 adjacent to exactly two 0's. 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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 03 2011
STATUS
approved

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Last modified June 17 18:04 EDT 2024. Contains 373463 sequences. (Running on oeis4.)