This is an excellent example of something Michael R Fellows called "Game Handles" if I remember right. Basically, the notion is that there are gamifiable structures in mathematics (and in his specialty, computer science) that one should be able to embody in interesting games (this was 1994 or earlier, long before "serious games" were cool :) ). Described in some detail here:
http://www.mrfellows.net/papers/C32-games.pdf
Anyway--there are the existing games "2048" and "Powers of 2" that use a similar dynamic to this, and merely by the fact that one is familiar with another sequence, one is able to "turn the handle on the math machine" and crank out an interesting game from it.
I don't mean any disrespect--the author thought this out and worked out what would be needed to move from the significantly more straightforward operations of the predecessor games to a sequence that becomes much more complex to move back and forth in in your head. The introduction of "out of sequence numbers" is unique to my knowledge (at least it is not in those two most popular instances).
I've only played through one time, but I'm very interested in playing again and itching to start working out what kinds of algorithms/heuristics might be employed. All in all, very well done.
mike