An automatic sequence (or k-automatic sequence) is an infinite sequence of terms characterized by a finite automaton. The n-th term of the sequence is a mapping of the final state of the automaton when its input is the digits of n in some fixed base k. A k-automatic set is a set of non-negative integers for which the sequence of values of its characteristic function is an automatic sequence: that is, membership of n in the set can be determined by a finite state automaton on the digits of n in base k.
An automaton reading the base k digits from the most significant is said to be direct reading, and from the least signficant is reverse reading. However the two directions lead to the same class of sequences.
Every automatic sequence is a morphic word.
Read more about Automatic Sequence: Automaton Point of View, Substitution Point of View, Decimation, 1-automatic Sequences, Properties, Examples, Automatic Real Number
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—Edward Dahlberg (1900–1977)
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—Walter Benjamin (1892–1940)