A221314 -id:A221314

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A221313

Square root of number of nX4 arrays of occupancy after each element moves to some horizontal or vertical neighbor, with every occupancy equal to zero or two

+10
0

1, 4, 9, 23, 57, 142, 353, 878, 2183, 5428, 13496, 33556, 83432, 207441, 515770, 1282382, 3188443

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OFFSET

1,2

COMMENTS

Column 4 of A221314

LINKS

Table of n, a(n) for n=1..17.

FORMULA

Empirical: a(n) = 2*a(n-1) + 2*a(n-2) - a(n-3) - 2*a(n-4) - a(n-5). - Vaclav Kotesovec, May 23 2013

EXAMPLE

Some solutions for n=3

..2..2..0..0....2..2..2..0....2..2..0..0....0..2..2..0....0..2..2..0

..0..2..0..2....2..0..0..0....2..0..0..2....2..2..0..0....0..0..0..0

..0..2..0..2....0..0..2..2....0..0..2..2....0..0..2..2....2..2..2..2

KEYWORD

nonn

AUTHOR

R. H. Hardin Jan 10 2013

STATUS

approved

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