  We fabricate high-mobility p-type few-layer WSe2 field-effect transistors and
surprisingly observe a series of quantum Hall (QH) states following an
unconventional sequence predominated by odd-integer states under a moderate
strength magnetic field. By tilting the magnetic field, we discover Landau
level (LL) crossing effects at ultra-low coincident angles, revealing that the
Zeeman energy is about three times as large as the cyclotron energy near the
valence band top at {\Gamma} valley. This result implies the significant roles
played by the exchange interactions in p-type few-layer WSe2, in which
itinerant or QH ferromagnetism likely occurs. Evidently, the {\Gamma} valley of
few-layer WSe2 offers a unique platform with unusually heavy hole-carriers and
a substantially enhanced g-factor for exploring strongly correlated phenomena.
