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A358709
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a(n) is the number of free, tree-like polyiamonds, of size 3*n+1, with 120-degree rotational symmetry formed of a central triangle and identical, non-intersecting snakes leading from each of its sides.
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1
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1, 1, 1, 2, 3, 6, 11, 20, 37, 66, 119, 217, 391, 706, 1274, 2289, 4133, 7435, 13384, 24068
(list;
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refs;
listen;
history;
text;
internal format)
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OFFSET
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0,4
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LINKS
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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