First check the python downloads page to view the current releases
$ open https://www.python.org/downloads/
This produces the list of ALL available pyenv versions
$ pyenv install --list
...
pypy3-dev
pypy3-2.3.1-src
pypy3-2.3.1
pypy3-2.4.0-src
pypy3-2.4.0
pypy3.3-5.2-alpha1-src
pypy3.3-5.2-alpha1
pypy3.3-5.5-alpha-src
pypy3.3-5.5-alpha
pypy3.5-c-jit-latest
pypy3.5-5.7-beta-src
pypy3.5-5.7-beta
pypy3.5-5.7.1-beta-src
pypy3.5-5.7.1-beta
pypy3.5-5.8.0-src
pypy3.5-5.8.0
pypy3.5-5.9.0-src
pypy3.5-5.9.0
pypy3.5-5.10.0-src
pypy3.5-5.10.0
pypy3.5-5.10.1-src
pypy3.5-5.10.1
pypy3.5-6.0.0-src
pypy3.5-6.0.0
pypy3.5-7.0.0-src
pypy3.5-7.0.0
pypy3.6-7.0.0-src
pypy3.6-7.0.0
pypy3.6-7.1.0-src
pypy3.6-7.1.0
pypy3.6-7.1.1-src
pypy3.6-7.1.1
pypy3.6-7.2.0-src
pypy3.6-7.2.0
pypy3.6-7.3.0-src
pypy3.6-7.3.0
pyston-0.5.1
pyston-0.6.0
pyston-0.6.1
stackless-dev
stackless-2.7-dev
stackless-2.7.2
stackless-2.7.3
stackless-2.7.4
stackless-2.7.5
stackless-2.7.6
stackless-2.7.7
stackless-2.7.8
stackless-2.7.9
stackless-2.7.10
stackless-2.7.11
stackless-2.7.12
stackless-2.7.14
stackless-3.2.2
stackless-3.2.5
stackless-3.3.5
stackless-3.3.7
stackless-3.4-dev
stackless-3.4.1
stackless-3.4.2
stackless-3.4.7
stackless-3.5.4
So that can be overwhelming.
Instead we can filter to see only python official distributions
pyenv install --list|awk '$1 ~ /^3/'
...
3.5.6
3.5.7
3.5.8
3.5.9
3.6.0
3.6-dev
3.6.1
3.6.2
3.6.3
3.6.4
3.6.5
3.6.6
3.6.7
3.6.8
3.6.9
3.6.10
3.7.0
3.7-dev
3.7.1
3.7.2
3.7.3
3.7.4
3.7.5
3.7.6
3.7.7
3.8.0
3.8-dev
3.8.1
3.8.2
3.9.0a5
3.9-dev
That is better but we still dont need every distribution
Here we filter the 10 most recent releases
pyenv install --list|awk '$1 ~ /^3/'|tail -n 10
3.7.4
3.7.5
3.7.6
3.7.7
3.8.0
3.8-dev
3.8.1
3.8.2
3.9.0a5
3.9-dev