The python script "problem-51.py" performs the straightforward but
tedious recursion involved in the solution of Problem 51. The script
deals with the case of Yang-Mills theory, but it it trivial to adapt
it to quantum field theories with other interactions.


It involves the following steps:

- the function Ts(n) computes the generating series for tree graphs
  with a leg singled out, up to n external legs

- the function Trees(n) extracts its coefficients and normalizes them
  to output the number of tree graphs up to n external legs

- the function Trees_ordered(n) computes the number of color ordered
  tree graphs up to n external legs


To run the script (inside a jupyter console), do:
    load "problem-51.py"


The output of the script is included in the file "output.txt"
