  Keating and Snaith modeled the Riemann zeta-function \zeta(s) by
characteristic polynomials of random NxN unitary matrices, and used this to
conjecture the asymptotic main term for the 2k-th moment of \zeta(1/2+it) when
k>-1/2. However, an arithmetical factor, widely believed to be part of the
leading term coefficient, had to be inserted in an ad hoc manner. Gonek, Hughes
and Keating later developed a hybrid formula for \zeta(s) that combines a
truncation of its Euler product with a product over its zeros. Using it, they
recovered the moment conjecture of Keating and Snaith in a way that naturally
includes the arithmetical factor. Here we use the hybrid formula to recover a
conjecture of Hughes, Keating and O'Connell concerning discrete moments of the
derivative of the Riemann zeta-function averaged over the zeros of \zeta(s),
incorporating the arithmetical factor in a natural way.
