The On-Line Encyclopedia of Integer Sequences (OEIS)

A185829 revision #7

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

(list; graph; refs; listen; history; text; internal format)

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: A245428 A307307 A377068 * A301664 A335803 A259136

Adjacent sequences: A185826 A185827 A185828 * A185830 A185831 A185832

KEYWORD

nonn

AUTHOR

R. H. Hardin Feb 05 2011

STATUS

approved