The minimal excludant of a partition λ λ, mex(λ) mex (λ), is the smallest positive integer that is not a part of λ λ. For a positive integer n n, σmex(n) σ mex (n) denotes the sum of the minimal ...

is a stipendiary lecturer in mathematics at Mansfield College, University of Oxford. She did her DPhil at the University of Oxford. It is a hot July day in London and I take the bus to Bloomsbury. I ...