  The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN)
association is the core collapse of massive stars. One possible outcome of such
a collapse is a rapidly spinning, strongly magnetized neutron star
("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN
associations detected by several instruments before 2017 June. Twenty GRB/SN
systems have been confirmed via direct spectroscopic evidence or a clear light
curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We
derive/collect the basic physical parameters of the GRBs and the SNe, and look
for correlations among these parameters. We find that the peak brightness, $\rm
^{56}Ni$ mass, and explosion energy of SNe associated with GRBs are
statistically higher than other Type Ib/c SNe. A statistically significant
relation between the peak energy of GRBs and the peak brightness of their
associated SNe is confirmed. No significant correlations are found between the
GRB energies (either isotropic or beaming-corrected) and the supernova energy.
We investigate the energy partition within these systems and find that the
beaming-corrected GRB energy of most systems is smaller than the SN energy,
with less than 30\% of the total energy distributed in the relativistic jet.
The total energy of the systems is typically smaller than the maximum available
energy of a millisecond magnetar ($2\times 10^{52}$ erg), especially if
aspherical SN explosions are considered. The data are consistent with-though
not a proof of-the hypothesis that most, but not all, GRB/SN systems are
powered by millisecond magnetars.
