Haus-Endt-Straße 88, 40593 Düsseldorf, Germany.
Accepted: 24 March 2016
The well-known expansion of rational integers in an arbitrary integer base different from 0,1, − 1 is exploited to study relations between numerical monoids and certain subsemigroups of the multiplicative semigroup of nonzero integers.
Mathematics Subject Classification: 11N25 / 20M14 / 11D07
Key words: Numerical monoid / digital representation / digital semigroup / Frobenius number
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