A183331 Number of n X 3 binary arrays with each 1 adjacent to exactly two 0's.

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

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