A211953 - OEIS

%I #7 Nov 08 2013 23:36:29

%S 6,20,102,520,2628,13482,68747,354500,1840433

%N Number of distinct regular languages over 4-ary alphabet, whose minimum regular expression has ordinary length n.

%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]

%K nonn,hard

%O 1,1

%A _Hermann Gruber_, Apr 26 2012