Title: Zeros of L-functions and Euler's idoneal numbers

Abstract: Assuming the Generalized Riemann Hypothesis, Weinberger
showed the only discriminants of definite binary quadratic forms with
one class per genus are the examples already known to Euler.
Unconditionally there is at most one more such example. Generalizing a
technique of Montgomery-Weinberger, we show there is no such example in
the range 10^100 < d < 10^28000.