  In SIAM Review 10, page 273, D. W. Matula described a bijection between N and
the set of topological rooted trees; the number is called the Matula number of
the rooted tree. The Gutman-Ivic-Matula (GIM) function g(n) computes the number
of edges of the unique tree with Matula number n. Since there is a prefix-free
code for the set of prime numbers such that the codelength of each prime p is
2g(p), we show how some properties of the GIM function can be obtained
trivially from coding theorems.
