A228679 Number of nX4 binary arrays with no two ones adjacent horizontally, diagonally or antidiagonally.

8, 40, 216, 1152, 6160, 32928, 176032, 941056, 5030848, 26894720, 143778176, 768632832, 4109082880, 21967006208, 117434808832, 627802177536, 3356207397888, 17942161561600, 95918137153536, 512774840614912

Offset

1,1

Comments

Column 4 of A228683

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 6*a(n-1) -2*a(n-2) -8*a(n-3).

Empirical: G.f. -8*x*(-1+x+x^2) / ( 1-6*x+2*x^2+8*x^3 ). - R. J. Mathar, Aug 31 2013

Example

Some solutions for n=4
..0..0..1..0....0..1..0..1....1..0..0..0....0..0..0..1....1..0..0..1
..0..0..0..0....0..0..0..1....0..0..0..1....1..0..0..0....1..0..0..0
..1..0..1..0....1..0..0..0....0..0..0..1....1..0..0..1....0..0..0..0
..1..0..1..0....0..0..0..0....1..0..0..1....1..0..0..0....1..0..0..0

Crossrefs

Sequence in context: A037703 A272396 A051199 * A188234 A068775 A068774

Adjacent sequences: A228676 A228677 A228678 * A228680 A228681 A228682

Keyword

nonn

Author

R. H. Hardin Aug 30 2013

Status

approved