A211942 Number of distinct finite languages over binary alphabet, whose minimum regular expression has reverse Polish length 2n-1.

4, 7, 25, 109, 514, 2641, 14354, 81325, 475936, 2854145

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Hermann Gruber, Jonathan Lee, and Jeffrey Shallit, Enumerating regular expressions and their languages, arXiv:1204.4982v1 [cs.FL], 2012.

Crossrefs

Sequence in context: A276288 A219700 A151348 * A110413 A075686 A077441

Adjacent sequences: A211939 A211940 A211941 * A211943 A211944 A211945

Keyword

nonn,hard

Author

Hermann Gruber, Apr 26 2012

Status

approved