@rowanmikaio,
It can't be a number-to-letter sequence, because we don't know a majority of the numbers. There needs to be a discernible pattern that will allow us to get an equation for finding the nth term. We need to work under the assumption that we WON'T know the other 300-something numbers in the sequence, and that we don't NEED to know them.
I tried subtracting the second number from the first, then the third from the second, and so on so forth. Through that, I got the following sequence:
50, 84, 78, 84, 49, 39, 83, 84, 49, 50, 54, 80, 116
Thought I had something when 84 kept appearing (which coincidentally is the first number in the sequence), but then the pattern devolved into gibberish.