A228756 Number of 4 X n binary arrays with top left element equal to 1 and no two ones adjacent horizontally or antidiagonally.

8, 21, 168, 780, 4599, 24246, 134440, 728537, 3988862, 21739002, 118720559, 647758554, 3535719686, 19295840383, 105313615878, 574764393110, 3136909949941, 17120293581344, 93437607513222, 509954720089427

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 20*a(n-2) + 27*a(n-3) - 14*a(n-4) - 25*a(n-5) + 4*a(n-6) + 5*a(n-7) - a(n-8).

Empirical g.f.: x*(8 + 13*x - 13*x^2 - 24*x^3 + 4*x^4 + 5*x^5 - x^6) / ((1 + x)*(1 + 2*x - x^2)*(1 - 4*x - 9*x^2 + 5*x^3 + 4*x^4 - x^5)). - Colin Barker, Sep 13 2018

Example

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

Crossrefs

Row 4 of A228754.

Sequence in context: A358720 A240648 A231525 * A228504 A270552 A156239

Adjacent sequences: A228753 A228754 A228755 * A228757 A228758 A228759

Keyword

nonn

Author

R. H. Hardin, Sep 02 2013

Status

approved