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A259482
Number of states in smallest deterministic finite automaton that accepts exactly the strings over the alphabet {1,2,...,n} having all permutations of 12...n as subsequences.
2
2, 6, 44, 2014, 1651377
OFFSET
1,1
COMMENTS
The automaton is assumed to be "complete"; that is, there is a transition from every state on every letter.
Also, the length of the shortest string accepted by this automaton is the sequence A062714.
EXAMPLE
For n = 2 there is a 6-state automaton accepting (11*22*1 + 22*11*2)(1 + 2)*.
CROSSREFS
Cf. A062714.
Sequence in context: A171690 A259763 A219337 * A332757 A255015 A347984
KEYWORD
nonn,hard,more,nice
AUTHOR
Jeffrey Shallit, Jun 28 2015
EXTENSIONS
a(5) from Kevin Ryde, Aug 21 2020
STATUS
approved