  Results are reported from a search for supersymmetric particles in
proton-proton collisions in the final state with a single, high transverse
momentum lepton; multiple jets, including at least one b-tagged jet; and large
missing transverse momentum. The data sample corresponds to an integrated
luminosity of 2.3 inverse femtobarns at sqrt(s) = 13 TeV, recorded by the CMS
experiment at the LHC. The search focuses on processes leading to high jet
multiplicities, such as gluino pair production with gluinos to t t-bar
neutralino[1]. The quantity M[J], defined as the sum of the masses of the
large-radius jets in the event, is used in conjunction with other kinematic
variables to provide discrimination between signal and background and as a key
part of the background estimation method. The observed event yields in the
signal regions in data are consistent with those expected for standard model
backgrounds, estimated from control regions in data. Exclusion limits are
obtained for a simplified model corresponding to gluino pair production with
three-body decays into top quarks and neutralinos. Gluinos with a mass below
1600 GeV are excluded at a 95% confidence level for scenarios with low
neutralino[1] mass, and neutralinos with a mass below 800 GeV are excluded for
a gluino mass of about 1300 GeV. For models with two-body gluino decays
producing on-shell top squarks, the excluded region is only weakly sensitive to
the top squark mass.
