Journal of Integer Sequences, Vol. 24 (2021), Article 21.8.4

Generalization of a Result of Sylvester Related to the Frobenius Coin Problem

Damanvir Singh Binner
Department of Mathematics
Simon Fraser University
Burnaby, BC V5A 1S6


In a recent paper, the present author generalized a fundamental result of Gauss related to quadratic reciprocity, and also showed that the above result of Gauss is equivalent to a special case of a well-known result of Sylvester related to the Frobenius coin problem. In this note, we use this equivalence to show that the above generalization of the result of Gauss naturally leads to an interesting generalization of the result of Sylvester. To be precise, for given positive coprime integers a and b, and for a family of values of k in the interval 0 ≤ k < (a – 1)(b – 1), we find the number of nonnegative integers ≤ k that can be expressed in the form ax + by for nonnegative integers x and y. We also give an elementary proof of Eisenstein's lemma for Jacobi symbols using floor function sums. Our proof provides a natural straightforward generalization of the Gauss-Eisenstein proof of the law of quadratic reciprocity for Jacobi symbols.

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Received July 10 2021; revised versions received July 20 2021; July 23 2021; August 6 2021; August 10 2021. Published in Journal of Integer Sequences, August 17 2021.

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