I was checking exactly the same the other day, hi everyone im new into this puzzle, and im obsessed with it. Spend hours and hours looking for a pattern, and there is no pattern as the "owner" mentioned it but i was looking for the already found keys and i think i found something.
If someone is brute forcing this, you need to start from eb851eb851eb8000 to ffffffffffffffff, thats why this is not still be found, the hex is almost at the end of the range. Im bruteforcing this from feb851eb851eb800 to ffffffffffffffff at 25 MKey/s (yes is a little slow but is honest work
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)
) and i will be checking from the back after finish a range.
I hope this helps anyone, and if i do please share something as i will share to 2 users of this forum (if i find the key) who gives me the idea
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
Regards from AR and sorry about my english.