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A266862
Number of 3Xn arrays containing n copies of 0..3-1 with no element 1 greater than its north or southwest neighbor modulo 3 and the upper left element equal to 0.
2
1, 4, 17, 66, 324, 1565, 7908, 41440, 219394, 1181538, 6433652, 35322999, 195435804, 1087909500, 6087937840, 34225256140, 193178201178, 1094225487556, 6217602330366, 35429358636014, 202398423255902, 1158911705466210
OFFSET
1,2
COMMENTS
Row 3 of A266861.
LINKS
EXAMPLE
Some solutions for n=4
..0..2..1..1....0..2..1..0....0..2..0..1....0..1..0..2....0..1..1..2
..0..2..1..0....2..1..1..0....2..1..2..0....2..1..0..2....2..1..0..2
..0..2..1..2....2..1..0..2....1..0..1..2....2..1..0..1....2..0..0..1
CROSSREFS
Cf. A266861.
Sequence in context: A291394 A244616 A030529 * A239845 A081113 A368429
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2016
STATUS
approved