  Let Sn denote the network of all RNA secondary structures of length n, in
which undirected edges exist between structures s, t such that t is obtained
from s by the addition, removal or shift of a single base pair. Using
context-free grammars, generating functions and complex analysis, we show that
the asymptotic average degree is O(n) and that the asymptotic clustering
coeffcient is O(1/n), from which it follows that the family Sn, n = 1,2,3,...
of secondary structure networks is not small-world.
