Help needed in analyzing sequential data

I hope for your advice and directions:
I've data that codes a sequence of behaviors. Each sequences is of different lengths. I have 1400 sequences from 200 participants. I want to find patterns in these sequences, and then to group similar patterns together.

My questions are:
1. What field of mathematics and statistics cover this area?
2. What statistical procedures can I use to analyze this data?

Sorry if this is not the correct forum for these questions, but I'm not sure where to ask.