Brewer sum
In mathematics, Brewer sums are finite character sum introduced by Brewer (1961, 1966) related to Jacobsthal sums.
The Brewer sum is given by
where Dn is the Dickson polynomial (or "Brewer polynomial") given by
and () is the Legendre symbol.
The Brewer sum is zero when n is coprime to q2−1.
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