As an example of just how arbitrary Gödel numbers are, consider the expressions `((3*n)+1)` and `((n*3)+1)`. Those expressions are clearly equivalent, yet the Gödel numbers for those two expressions are wildly different, with a relation that is rather complex.
IIUC Gödel himself never "used" or analyzed Gödel numbers as such, only the idea that they could be constructed.