A228278 - OEIS

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A228278

Number of n X 3 binary arrays with top left value 1 and no two ones adjacent horizontally, vertically or nw-se diagonally.

2, 3, 13, 35, 112, 337, 1034, 3154, 9637, 29431, 89895, 274564, 838609, 2561372, 7823242, 23894643, 72981777, 222909351, 680835436, 2079486057, 6351405998, 19399196250, 59251261117, 180972030923, 552745635451, 1688259428536

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

OFFSET

1,1

COMMENTS

Column 3 of A228285.

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 + x - x^3) / ((1 + x)*(1 - 2*x - 3*x^2 - x^3 + x^4)). - Colin Barker, Mar 16 2018

EXAMPLE

Some solutions for n=4:

..1..0..0....1..0..0....1..0..0....1..0..1....1..0..0....1..0..1....1..0..0

..0..0..0....0..0..0....0..0..1....0..0..0....0..0..0....0..0..0....0..0..0

..0..0..1....0..0..0....0..0..0....0..0..0....1..0..0....0..0..1....0..1..0

..0..0..0....1..0..1....1..0..0....0..1..0....0..0..1....0..1..0....1..0..0

CROSSREFS

See A228277-A228285, especially the latter.

Sequence in context: A216359 A169983 A151461 * A174742 A215279 A082539

Adjacent sequences: A228275 A228276 A228277 * A228279 A228280 A228281

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 19 2013

EXTENSIONS

Edited by N. J. A. Sloane, Aug 22 2013

STATUS

approved