  With the black hole mass function (BHMF; assuming an exponential cutoff at a
mass of $\sim 40\,M_\odot$) of coalescing binary black hole systems constructed
with the events detected in the O1 run of the advanced LIGO/Virgo network,
Liang et al.(2017) predicted that the birth of the lightest intermediate mass
black holes (LIMBHs; with a final mass of $\gtrsim 100\,M_\odot$) is very
likely to be caught by the advanced LIGO/Virgo detectors in their O3 run. The
O1 and O2 observation run data, however, strongly favor a cutoff of the BHMF
much sharper than the exponential one. In this work we show that a power-law
function followed by a sudden drop at $\sim 40\,M_\odot$ by a factor of $\sim
$a few tens and then a new power-law component extending to $\geq 100M_\odot$
are consistent with the O1 and O2 observation run data. With this new BHMF,
quite a few LIMBH events can be detected in the O3 observation run of advanced
LIGO/Virgo. The first LIMBH born in GW190521, an event detected in the early
stage of the O3 run of advanced LIGO/Virgo network, provides additional
motivation for our hypothesis.
