A211953 - OEIS

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A211953

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

0

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

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..9.

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

CROSSREFS

Sequence in context: A333048 A200538 A238118 * A266846 A207819 A297974

Adjacent sequences: A211950 A211951 A211952 * A211954 A211955 A211956

KEYWORD

nonn,hard

AUTHOR

Hermann Gruber, Apr 26 2012

STATUS

approved