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Number of distinct finite languages over 3-ary alphabet, whose minimum regular expression has reverse Polish length 2n-1.
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%I #14 Feb 22 2021 13:23:01

%S 5,15,85,589,4512,37477,328718,2998039

%N Number of distinct finite languages over 3-ary alphabet, whose minimum regular expression has reverse Polish length 2n-1.

%H Hermann Gruber, Jonathan Lee, and Jeffrey Shallit, <a href="http://arxiv.org/abs/1204.4982">Enumerating regular expressions and their languages</a>, arXiv:1204.4982v1 [cs.FL], 2012.

%K nonn,hard

%O 1,1

%A _Hermann Gruber_, Apr 26 2012