Coefficients of Waiting Time Polynomials: a nice representation

I was doing some simulation for the paper I'm writing about the waiting time polynomials, and I got something unexpected.
If we sort in lexicographic order all the polynomials generated for a given length of the events vector, and we consider the coefficients, what  you get is an apparently irregular series of integers.
To capture some regularity, I decided to plot such matrix:

The matrix plot, obtained considering an alphabet of three words and vectors having length=35.

Isn't nice?
Sometimes, an appropriate graphical representation helps in capture interesting aspects of your data

Stay Tuned
Cristian