  We present preliminary results for the curvature of the pseudocritical line
and susceptibilities in Nf = 2 + 1 flavor QCD. The computations are carried out
on lattice sizes of 16x16x16x4, at matching parameters of early work of the
Bielefeld group. Emphasis is placed on the control of systematic errors, by
cross-validating results obtained by use of the Taylor expansion and
measurements at imaginary chemical potential. To this end, we generalize the
magnetic equation of state to the analysis of the number density, and we extend
it to imaginary values of the chemical potential.
