That sounds strange -- accessing api.telegram.org
should work fine. I ran the code you posted above in a free account, and it looks like it worked to me:
Python 3.7.0 (default, Aug 22 2018, 20:50:05)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests as req
>>> a = req.get('https://api.telegram.org')
>>> a.status_code
200
>>> a.content
b'<!DOCTYPE html>\n<html>\n <head>\n <meta charset="utf-8">\n <title>Bots: An introduction for developers</title>\n <meta name="
viewport" content="width=device-width, initial-scale=1.0">\n <meta property="description" content="Bots are third-party applications th
...
What happens when you run it?