Interacting with program after execution

in Pycharm, Run/Debug menu choose Edit Configuration, check the box before 'Show command line afterwards'

Click Run -> Edit Configurations...,

Then check the box Run with Python console.

UPDATE
Starting with version 4.0 there's an option Show command line afterwards (renamed in later versions to Run with Python console) when editing run/debug configuration in Run|Edit Configurations....

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From output of python --help:

-i : inspect interactively after running script; forces a prompt even if stdin does not appear to be a terminal; also PYTHONINSPECT=x

To set interpreter option in PyCharm go to Run|Edit Configuration