|
|
A221329
|
|
Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.
|
|
1
|
|
|
1, 17, 119, 866, 6328, 46211, 337274, 2460918, 17953576, 130970758, 955393448, 6969190236, 50836821440, 370827923908, 2704988609708, 19731401249156, 143929610463264, 1049886222652688, 7658333144969252, 55863255070913284
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 11*a(n-1) - 27*a(n-2) - a(n-3) + 8*a(n-4) - 16*a(n-5) - 6*a(n-6) + 2*a(n-7) for n>9.
Empirical g.f.: x*(1 + 6*x - 41*x^2 + 17*x^3 + 24*x^4 - 16*x^5 + x^6 + 5*x^7 - x^8) / (1 - 11*x + 27*x^2 + x^3 - 8*x^4 + 16*x^5 + 6*x^6 - 2*x^7). - Colin Barker, Aug 05 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..0..1..0....1..1..1....2..0..1....2..1..0....0..1..1....2..0..2....1..0..1
..1..2..2....2..0..1....1..0..2....2..1..0....1..1..2....0..1..1....1..1..2
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|