Michio, Are you trying to open the ipynb file with python? You need Jupyter Notebook to run ipynb files. Try installing jupyter notebook (cmd: pip install jupyter) then launching the jupyter notebook py server (cmd: jupyter notebook). You should be able to use the file browser in the notebook window to open the file.
I'm not sure about your familiarity with Jupyter/python, sorry if this is off base. -E -- https://mail.python.org/mailman/listinfo/python-list
