I tried that, but found that guessing backwards from the current time works better: https://gist.github.com/Aaron1011/2595f8699ade9d4df16398a68e...
$ curl -I https://permanent-redirect.xyz/pages/1515222320
HTTP/1.1 200 OK
Date: Fri, 12 Jan 2018 15:07:09 GMT
Server: Apache
Content-Type: text/html; charset=UTF-8The idea behind my script is that the URL is encoding the unix time of the first visit to that URL. By starting at the current time and working backwards, the first HTTP 200 you come across should be the current page.