RNAshapes
Supplement to "Asymptotics of RNA shapes"
by W.A. Lorenz, Y. Ponty and P. Clote, submitted

supplementary.pdf: PDF file with
complete proof, including all details, for the number of pishapes
compatible with an RNA sequence of length n, assuming that any base
can basepair with any other base, and that there are at least 3
unpaired bases in each hairpin loop.
Mathematica code and html files for various computations

Number of pishapes of length n:
HTML,
Mathematica code

Number of pishapes compatible with length n secondary structures:
HTML,
Mathematica code

Number of piPrimeshapes of length n:
HTML,
Mathematica code

Number of piPrimeshapes compatible with length n secondary structures:
HTML,
Mathematica code
Maple code and html files for various computations

Combinatorial proof of a onetoone correspondence between pishapes and Motzkin words [html][Maple]

A linear recurrence for the number of pishapes [html][Maple]