Finding versions of Python that are available for "pyenv install"
pyenv accepts a switch to the install command to list available versions: --list, or -l for short:
$ pyenv install -l
Available versions:
2.1.3
2.2.3
2.3.7
2.4.0
2.4.1
2.4.2
...
Before running pyenv install -l, you may need to update pyenv as described here. Otherwise the list may not include the latest versions (thank you @csatt1).