  We for the first time map the range of active-sterile neutrino mixing angles
in which leptogenesis is possible in the type I seesaw model with three heavy
neutrinos with Majorana masses between 50 MeV and 100 TeV, covering the entire
experimentally accessible mass range. Our study includes both,the asymmetry
generation during freeze-in (ARS mechanism) and freeze-out (resonant
leptotenesis) of the heavy neutrinos. The range of mixings for which
leptogenesis is feasible is considerably larger than in the minimal model with
only two heavy neutrinos and extends all the way up to the current experimental
bounds. For such large mixing angles the HL-LHC could potentially observe a
number of events that is large enough to compare different decay channels, a
first step towards testing the hypothesis that these particles may be
responsible for the origin of matter and neutrino masses.
