  We show that a 1969 result of Bouwkamp and de Bruijn on a formal power series
expansion can be interpreted as the hypergraph analogue of the fact that every
connected graph with n vertices has at least n-1 edges. We explain some of
Bouwkamp and de Bruijn's formulas in terms of hypertrees and we use Lagrange
inversion to count hypertrees by the number of vertices and the number of edges
of a specified size.
