

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
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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



