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A260938
Number of balanced ternary words of length n.
1
1, 3, 9, 27, 63, 141, 249, 435, 663, 969, 1293, 1713, 2169, 2751, 3333, 4047, 4827, 5733, 6711, 7875, 9081, 10437, 11817, 13425, 15171, 17091, 19017, 21183, 23475, 26001, 28611, 31521, 34515, 37755, 41067, 44631, 48363, 52389, 56499, 60915, 65493, 70419, 75417
OFFSET
0,2
COMMENTS
A word w is balanced if, for every pair of factors (consecutive blocks occurring within it) of the same length, the number of occurrences of each letter in the two factors differs by at most 1. For example, the word "banana" has this property.
LINKS
EXAMPLE
a(4) = 63, since all words of length 4 are balanced except 0011, 0012, 0021, 0022, 0122, 0211 (and renamings of those).
CROSSREFS
Cf. A005598.
Sequence in context: A097803 A227097 A201202 * A274626 A161712 A280466
KEYWORD
nonn
AUTHOR
Jeffrey Shallit, Aug 04 2015
EXTENSIONS
More terms from Lars Blomberg, Dec 10 2015
STATUS
approved