Counting subgroups in a family of nilpotent semi-direct products
  In this paper we compute the subgroup zeta functions of nilpotent semi-direct products of groups of the form   $$G_n=<x_1,...,x_n,y_1,...,y_{n-1}|[x_i,x_n]=y_i, 1\leq i\leq n-1, \text{all other $[,]$ trivial}>$$   and deduce local functional equations. 
Christopher Voll