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

Author

R. H. Hardin, Sep 02 2013

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Row 4 of A228754.

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