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A266868
Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its west or northeast neighbor modulo 3 and the upper left element equal to 0.
2
2, 4, 17, 57, 207, 786, 3057, 12168, 49161, 200973, 830381, 3462433, 14543365, 61455313, 261051074, 1114132113, 4775036853, 20540793414, 88645205402, 383652117835, 1664756627492, 7241001588378, 31563853315709, 137860267982920
OFFSET
1,1
COMMENTS
Row 3 of A266867.
LINKS
EXAMPLE
Some solutions for n=4
..0..2..1..0....0..2..2..2....0..0..2..2....0..0..2..2....0..0..0..2
..2..1..0..2....1..1..1..1....0..2..1..1....2..1..1..0....2..2..1..1
..1..0..2..1....0..0..0..2....2..1..1..0....1..1..0..2....1..1..0..2
CROSSREFS
Cf. A266867.
Sequence in context: A018269 A270359 A276557 * A203177 A096122 A014522
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2016
STATUS
approved