A211946 Number of distinct finite languages over 4-ary alphabet, whose minimum regular expression has reverse Polish length 2n-1.

6, 26, 202, 1917, 20251, 231152, 2780936

Offset

1,1

Links

Table of n, a(n) for n=1..7.

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

Crossrefs

Bisection of A211945.

Sequence in context: A049040 A103649 A053946 * A027283 A009639 A323868

Adjacent sequences: A211943 A211944 A211945 * A211947 A211948 A211949

Keyword

nonn,hard,more

Author

Hermann Gruber, Apr 26 2012

Status

approved