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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
8, 21, 168, 780, 4599, 24246, 134440, 728537, 3988862, 21739002, 118720559, 647758554, 3535719686, 19295840383, 105313615878, 574764393110, 3136909949941, 17120293581344, 93437607513222, 509954720089427 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 02 2013
STATUS
approved

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Last modified June 21 12:50 EDT 2024. Contains 373544 sequences. (Running on oeis4.)