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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 (list; graph; refs; listen; history; text; internal format)
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

Lars Blomberg, Table of n, a(n) for n = 0..170

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

Adjacent sequences:  A260935 A260936 A260937 * A260939 A260940 A260941

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, Aug 04 2015

EXTENSIONS

More terms from Lars Blomberg, Dec 10 2015

STATUS

approved

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Last modified August 10 19:52 EDT 2020. Contains 336381 sequences. (Running on oeis4.)