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

%I #11 Sep 13 2018 06:08:03

%S 8,21,168,780,4599,24246,134440,728537,3988862,21739002,118720559,

%T 647758554,3535719686,19295840383,105313615878,574764393110,

%U 3136909949941,17120293581344,93437607513222,509954720089427

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

%H R. H. Hardin, <a href="/A228756/b228756.txt">Table of n, a(n) for n = 1..210</a>

%F 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).

%F 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

%e Some solutions for n=4:

%e ..1..0..1..0....1..0..0..0....1..0..0..0....1..0..0..0....1..0..0..1

%e ..0..0..0..0....0..0..0..0....0..0..0..1....1..0..1..0....1..0..0..0

%e ..0..0..0..0....0..0..0..1....0..0..0..0....0..0..0..1....0..0..1..0

%e ..0..1..0..0....1..0..0..1....1..0..0..0....0..0..0..0....1..0..0..1

%Y Row 4 of A228754.

%K nonn

%O 1,1

%A _R. H. Hardin_, Sep 02 2013

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Last modified July 23 18:56 EDT 2024. Contains 374553 sequences. (Running on oeis4.)