You missed my edited post... Here it is:
35.9m as of Jan 3rd 2016
53.4m as of Jan 1st 2017
( and it was 18.5m as of Jan 4th 2015, of which the 4.1m were from 2013 nov-dec, launch months )
So you're completely correct!
I think it sold 4.1m in nov-dec 2013, not 4.2m... lol Not that it makes any difference!
i just googled "PS4 sales 2013" and a few articles popped up saying 4.2 million.
When the herd loses its way, the shepard must kill the bull that leads them astray.