How to predict the next value in a table? [closed]

I have a table full of values. I want to know what the next values may be.

PostgreSQL cannot look into the future, but it can guess based on existing data.

I will not install any software or extensions.

I have not hooked this script up to a syringe full of poison which sticks me if it predicts the wrong number, nor will this mechanism be auto-trading on the stock market. I will not sue anyone if it predicts the wrong number. It will be used "for novelty purposes only".

What would be the most likely "algorithm" to stand the best chance of guessing the next value?

If I just do:

SELECT avg(integer_column) FROM table; 

I will get the average number. That seems like a reasonable guess, but it also seems a bit simplistic. It seems like it could do better than that, without getting into some kind of crazy, ultra-complex query.