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A228662
Number of 3 X n binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally.
1
4, 5, 34, 78, 335, 968, 3556, 11245, 38986, 127662, 433015, 1437072, 4833924, 16125205, 54068594, 180718798, 605223135, 2024416088, 6776576996, 22673534845, 75884451226, 253927226542, 849793486215, 2843728075552, 9516580935684
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - 5*a(n-3).
Empirical g.f.: x*(4 - 3*x) / (1 - 2*x - 6*x^2 + 5*x^3). - Colin Barker, Sep 12 2018
EXAMPLE
Some solutions for n=4:
..1..0..1..0....1..0..0..0....1..0..0..0....1..0..0..1....1..0..0..0
..0..0..0..0....0..0..0..0....0..0..0..1....0..0..0..1....0..0..0..0
..0..1..0..0....0..0..0..0....1..0..0..0....0..1..0..1....1..0..0..1
CROSSREFS
Row 3 of A228660.
Sequence in context: A376536 A244333 A041907 * A151450 A243772 A332316
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 29 2013
STATUS
approved