A228477 Number of nX3 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically or antidiagonally.

2, 4, 14, 41, 127, 386, 1181, 3605, 11013, 33635, 102734, 313780, 958385, 2927208, 8940618, 27307464, 83405606, 254747013, 778077691, 2376494562, 7258563605, 22169941573, 67713990833, 206819875427, 631693101322, 1929389878184

Offset

1,1

Comments

Column 3 of A228482

Same recurrences as A228285 except in addition a smaller one for column 5

Links

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

Formula

a(n) = a(n-1) +5*a(n-2) +4*a(n-3) -a(n-5).

G.f.: -x*(-2-2*x+x^3) / ( (1+x)*(x^4-x^3-3*x^2-2*x+1) ). - R. J. Mathar, Aug 25 2013

Example

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

Crossrefs

Sequence in context: A279322 A152011 A000912 * A360182 A169982 A367101

Adjacent sequences: A228474 A228475 A228476 * A228478 A228479 A228480

Keyword

nonn

Author

R. H. Hardin Aug 22 2013

Status

approved