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A221126
Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor.
1
1, 21, 200, 1950, 19005, 185164, 1803949, 17574675, 171218008, 1668058947, 16250746331, 158319795778, 1542400400537, 15026541578483, 146393213915408, 1426207951308175, 13894558811577567, 135365087812821450
OFFSET
1,2
COMMENTS
Row 2 of A221125.
LINKS
FORMULA
Empirical: a(n) = 11*a(n-1) - 11*a(n-2) - 12*a(n-3) - 2*a(n-4) for n>6.
Empirical g.f.: x*(1 + 10*x - 20*x^2 - 7*x^3 + 9*x^4 + x^5) / (1 - 11*x + 11*x^2 + 12*x^3 + 2*x^4). - Colin Barker, Aug 04 2018
EXAMPLE
Some solutions for n=3:
..0..1..0....1..0..2....1..2..0....1..2..0....0..3..1....1..1..1....0..1..0
..2..3..0....0..1..2....2..0..1....1..2..0....0..0..2....1..0..2....2..1..2
CROSSREFS
Cf. A221125.
Sequence in context: A058086 A270957 A159857 * A239418 A337897 A341399
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2013
STATUS
approved