The numbers can be rewritten as:
Therefore, the next term should take the form of:
As for the $x$, I found that it increased by 0.5 or 1 every time, although I don't really know the exact pattern. So I think the answer is
A partial answer only at this point, I am still working on this and hope to come back to it later!
My suspicion is that this relates to
More specifically, I think that
I need to do some more digging to find out how the characters would map to the square to make this work out and decode it.
Update: No matter which way out I label the squares (a-z0-9, 0-9a-z,...
The first rebus, figured out by Feryll, is a hint to:
The second rebus shows:
Then, based on the Morse code deciphered by Feryll, we are supposed to:
This is clued by the axis labels and the first half of the Morse code:
The result is the string:
Then using Feryll's correct identification of the image hosting site in question, one can convert this to a ...