A185829 Half the number of nX3 binary arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

1, 10, 30, 118, 393, 1430, 5004, 17877, 63181, 224324, 794939, 2819380, 9995857, 35445025, 125677385, 445630567, 1580102608, 5602722348, 19866041906, 70440800557, 249768066156, 885624613914, 3140236676877, 11134612682393

Offset

1,2

Comments

Column 3 of A185835

Links

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

Formula

Empirical: a(n)=2*a(n-1)+6*a(n-2)-a(n-3)-3*a(n-4)+4*a(n-5)-4*a(n-6)-32*a(n-7)-9*a(n-8)-4*a(n-9)-19*a(n-10)+17*a(n-11)+3*a(n-12)+a(n-13)-a(n-14)

Example

Some solutions for 4X3 with a(1,1)=0
..0..1..1....0..0..0....0..0..0....0..0..1....0..1..1....0..0..0....0..0..0
..0..0..0....1..1..0....1..1..1....1..1..1....0..0..0....0..1..1....0..1..0
..1..1..1....0..0..1....0..0..1....1..0..0....1..1..0....0..1..0....0..1..0
..0..0..1....0..1..1....0..0..1....1..1..1....0..0..0....0..0..0....0..1..0

Crossrefs

Sequence in context: A115134 A245428 A307307 * A301664 A335803 A259136

Adjacent sequences: A185826 A185827 A185828 * A185830 A185831 A185832

Keyword

nonn

Author

R. H. Hardin Feb 05 2011

Status

approved