  Throughout the last 20 years 7 supernovae (SNe) have been discovered within
Arp 299. One of these is unclassified, leaving 6 core-collapse events; 2 type
II, 2 type Ib, a type IIb and one object of indistinct type; Ib/IIb. We analyse
the relative numbers of these types, together with their positions with respect
to host galaxy properties, to investigate implications for both progenitor
characteristics and star formation (SF) properties. Our findings are: 1) the
ratio of 'stripped envelope' (SE) events to other type II is higher than that
found in the local Universe. 2) All SE SNe are more centrally concentrated
within the system than the other type II. 3) All SN environments have similar
metallicities and there are no significant metallicity gradients across the
system. 4) The SE SNe all fall on bright SF regions while the other type II are
found to occur away from bright HII regions. We draw two different -but
non-mutually exclusive- interpretations on the system and its supernovae: 1)
The distribution of SNe, and the relatively high fraction of types Ib and IIb
events over other type II can be explained by the young age of the most recent
SF in the system, where insufficient time has expired for the observed to match
the 'true' relative SN rates. This explanation provides additional independent
evidence that both types Ib and IIb SNe arise from progenitors of shorter
stellar lifetime and hence higher mass than other type II. 2) Given the
assumption that types Ib and IIb trace higher mass progenitor stars, the
relatively high frequency of types Ib and IIb to other type II, and also the
centralisation of the former over the latter with respect to host galaxy light
implies that in the centrally peaked and enhanced SF within this system, the
initial mass function is biased towards the production of high mass stars.
