  We study a ferromagnetic instability in a single-band Hubbard model on the
hypercubic lattice away from half filling. Using dynamical mean-field theory
with the continuous-time quantum Monte Carlo simulations based on the segment
algorithm, we calculate the magnetic susceptibility in the weak and strong
coupling regions systematically. We then find how ferromagnetic fluctuations
are enhanced when the interaction strength and density of holes are varied. The
efficiency of the double flip updates in the Monte Carlo simulations is also
addressed.
