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A267223
Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its west, northeast or southeast neighbor modulo 3 and the upper left element equal to 0.
1
2, 3, 8, 17, 34, 68, 164, 385, 826, 1848, 4450, 10544, 24056, 56108, 135672, 324720, 762864, 1818110, 4413518, 10641004, 25427616, 61338160, 149415144, 362365684, 875207554, 2127235158, 5197934580, 12666448776, 30813494386, 75278796468
OFFSET
1,1
COMMENTS
Row 3 of A267222.
LINKS
EXAMPLE
Some solutions for n=4
..0..0..2..1....0..2..1..1....0..2..1..1....0..2..1..1....0..2..1..0
..2..1..0..2....2..1..0..2....1..0..0..2....2..1..0..2....1..0..2..1
..1..0..2..1....0..2..1..0....2..2..1..0....0..0..2..1....2..1..0..2
CROSSREFS
Cf. A267222.
Sequence in context: A210701 A158921 A064954 * A292401 A132333 A182889
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 12 2016
STATUS
approved