We are told that x, y are integers, so they might be zero or negative. I suspect Nimrod means positive integers. We are also told that they are 'terms in a mathematical series'. Does Nimrod mean terms of a sequence, and that there is some iteration rule ? I suspect this is what is intended, and so the puzzle has something to do with most 'famous' of all sequences. But of course 2, 3, 5, 37, 28953, 1, 1, 1, 11, ... is a sequence, and 2 +3 + 5 + 37 + 28953 + .... is part of a series. This sort of laxity in definition is not encouraging.
I will, in any case, need to solve a couple more clues, but I am not particularly looking forward to the 'spot the message' element.