Set partitions with no m-nesting
  A partition on [n] has an m-nesting if there exists i_1 < i_2 < ... < i_m < j_m < j_{m-1} < ... < j_1, where i_l and j_l are in the same block for all 1 <= l <= m. We use generating trees to construct the class of partitions with no m-nesting and determine functional equations satisfied by the associated generating functions.   We use algebraic kernel method together with a linear operator to describe a coefficient extraction process. This gives rise to enumerative data, and illustrates the increasing complexity of the coefficient formulas as m increases. 
Marni Mishna and Lily Yen
math.CO